a gun and grenades hidden behind an mri machine. a stash of guns in a closet. military gear and uniforms. israel calling it proof hamas is using the hospital as a command center. hamas denying that. and what about the potentially thousands of civilians including dozens of premature babies taking shelter there? our team embedded with israeli forces in gaza. also tonight, face-to-face, president biden greeting chinese leader xi jinping in california. can the two leaders find a path to ease tensions? the deadly bus crash investigation. what we're learning about the six killed including three students. our nbc news exclusive, never-before-seen footage from the alec baldwin movie "rust." baldwin seen firing a gun and speaking to the cinematographer later fatally shot. >> i'm going to shoot right. want me to go on the outside of the camera? >> it comes as baldwin faces potential new charges. and she's been called the michael jordan of field hockey making history as the ncaa's youngest division 1 head coach. >> announcer: this is "nbc nightly news" with lester holt. good evening, and welcome, everyone. the war of competing narratives and images heated up today in gaza where israeli troops stormed the al shifa hospital finding what they say is evidence of concealed hamas activities. the idf offering up video, not verified by nbc news, of weapons they say were discovered in hidden places including among mri machines in the hospital. israel has faced condemnation for its attacks on hospital facilities where unverified video released by gaza's health run ministry shows doctors scrambling to save lives during an israeli attack. the white house has called for patients to be protected saying it did not want to see a firefight in a hospital. prime minister netanyahu saying, there is no place in gaza they won't go to target hamas, but israel under growing outside pressure for the first time allowing some fuel shipments to ease the humanitarian crisis in gaza. in a moment, our correspondent on the ground in gaza city, but first here's keir simmons. >> reporter: just hours after israel launched what it calls a targeted raid, inside gaza's al shifa hospital, the israeli military releasing images it says shows hamas terrorist weapons found there including some ak-47s. while the hamas-run gaza health ministry releasing this video, smoke pouring into the hospital's intensive care unit, doctors pushing patients to safety. nbc news is unable to independently confirm either video, but an israeli spokesperson saying, they found proof of israeli and u.s. assertions that hamas has been operating in hospitals including hiding weapons behind medical equipment. >> there is an ak-47, there are cartridges and ammo, there are grenades in here, of course, uniforms, and all of this was hidden very conveniently, secretly behind the mri machine. >> reporter: inside closets. >> hamas put them here because they use this place. >> reporter: and behind explosive-proof doors. >> take a look at this door here. blast-proof door which is part of the clinic. >> reporter: so far it's not clear whether there are tunnels or a command center at the hospital. hamas rejecting the allegations, and a hospital doctor dismissing them tonight in a phone call. >> they released a video saying that they found weapons. the doctor describing the israeli raid as frightening. >> there's really aggressive bombing. gunshots all over the place. >> reporter: tonight he says they still need help for the 36 premature babies without working incubators while israel says it's provided incubators and baby food. the white house said they did not want to see a firefight in the hospital. prime minister netanyahu saying there is no place in gaza we will not reach to target hamas. israel is far from finished in gaza. today our camera crew filmed the aftermath of another air strike in the south while in the north, officials reported more bodies pulled from the rubble. meanwhile, an alarming warning in the u.s. the fbi director says following the hamas terror attacks, the threat of an attack on americans in the u.s. is at a, quote, whole other level. >> we've seen a rogue gallery of foreign terrorist organizations call for attacks against americans and our allies. >> keir, there's a lot at play here. there's also the urgent focus on the hostages still held by hamas including americans, and there's one heartbreaking development to report tonight. >> reporter: lester, it comes in a letter from prime minister netanyahu's wife to first lady jill biden, writing that a pregnant hostage has likely given birth in captivity writing, imagine what's going through that young mother's mind. >> tonight our raf sanchez reports from inside gaza with a firsthand look at the palestinians trying to make their way to safer ground. >> reporter: under the watchful eyes of israeli troops an exodus of palestinians from gaza city is under way. children with their hands up, their parents clutching i.d. cards. the white flag flying amid the destruction. >> we've been covering the war for more than a month, but this is the first time that we are seeing with our own eyes palestinian civilians inside of gaza. >> reporter: this is what israel's military calls a humanitarian corridor open a few hours each day for civilians to flee on foot and escape the fighting raging in gaza city. 250,000 palestinians have taken this route so far, israel says. as a condition of access, nbc news agreed to blur some faces and submit our raw footage to israel's military sensors, though not our final story. >> i think everyone, jew and israeli, can be proud of the fact that we're letting innocent civilians out of the fighting area, out of the fighting zone to clear it out. >> reporter: for israel this is proof their war is only against hamas, not the people of gaza. >> but for many palestinians this feels like forced displacement. >> we asked israel's military. can you guarantee that these people will be able to return home one day? >> i think that that is really going to be in the hands of a lot of different players, one of the main ones will be hamas. >> reporter: soldiers call out in hebrew in case hamas is smuggling hostages in the crowd. >> so they're like asking the children, put your arms up, put your arms up. we'll come and save you, don't worry. so far no sign of the hostages. israel believes they're hidden in hamas' vast network of tunnels like this shaft in a rural area near the border. >> we know that if you were to go through this and map out where this leads to, you would reach our hostages. >> reporter: they found nothing in this tunnel, now they're lowering explosives. moments later, israel searching for hostages held in darkness, palestinians heading into an exile of dust and despair. raf sanchez, nbc news, gaza city. >> we want to turn to today's historic meeting between president biden and china's xi jinping. both leaders emphasizing the importance of communicating with each other. peter alexander has late details. >> reporter: tonight president biden and china's president xi face-to-face. this greeting kicking off their first in-person visit in a year. an effort to restore one of the world's most consequential relationships, now at its lowest point in decades. >> it's paramount that you and i understand each other clearly, leader to leader, with no misconceptions or miscommunication. we have to ensure that competition does not veer into conflict. >> reporter: president xi appearing to acknowledge that tensions have escalated saying, the u.s./china relationship has never been smooth sailing but has always moved forward. planet earth is big enough for the two countries to succeed, president xi said adding, as long as they respect each other, they'll be fully capable of rising above their differences. still, those differences run deep. tonight white house advisers tell us they're looking to restart direct military-to-military talks. the collapse following the u.s. shooting down that chinese spy balloon. among other tension points, china's close ties with russia and iran, the threat of aggression toward taiwan, and china's theft of technology and hacking as fbi director christopher wray warned about again today. >> china alone has the biggest hacking program in the world by far. they're not slowing down. >> reporter: one expected takeaway, both sides agreeing to a joint working group to combat the illegal flow of fentanyl from china into the u.s. still, many republicans say president biden is not being tough enough with china. >> i think it represents, guys, a fundamental misunderstanding of this relationship by joe biden. we are in a great power struggle. they're hell bent on world domination. >> reporter: coming into tonight's meeting biden administration officials have repeatedly tried to lower any expectations of any major breakthroughs and just having the summit is progress, they say. lester. >> peter, thank you. let me bring in janis mackey frayer who covers china. this is being watched just as carefully in beijing. >> reporter: lester, optics are a key here. the images of xi jinping welcomed by president biden, the flag waving, even as chinese made limousine driving on american soil, they are all over state media and social media in china. the message, that he is a statesman who is respected by the u.s., the one country that for years has been officially vilified there for being a bully, trying to contain china's rise. so, a positive visit here for xi is a starting block for reshaping chinese public opinion, and it's also a strong sign that china's leadership is ready to engage again. >> yanis macke frayer, thank you. there are new developments in the fiery bus crash involving students in ohio. a federal investigation is now under way after six people were killed. rehema ellis with what we know about the victims. >> reporter: tonight, ntsb saying the investigation will take more than a year, but they're vowing to find out what caused the deadly crash in ohio killing three students, three chaperones, and injuring 15 others. >> our whole mission is based on determining how this happened, why this happened, and to prevent it from reoccurring. >> reporter: the fiery crash happened tuesday, about 25 miles from downtown columbus, the charter bus carrying mostly band members from tuscarawas valley high school on the way to a state conference. >> there are no words for the sheer magnitude of loss and grief felt by all of us. >> reporter: at a vigil last night, the reading of the victims' names. >> first is senior j.d. worrell. >> reporter: in a statement to nbc news his father george wrote, jeffery lived life with love and empathy for others. we are devastated. john mosely, also 18 years old, katelyn owens, a sophomore, was 15. also killed, three chaperones in the suv behind the bus. math teacher dave kennat was also the ski club adviser. >> would you call him one of your favorite teachers? >> oh, definitely, absolutely. he was just a great person. >> reporter: 39-year-old kristy gaynor was a wife and mother. shannon wigfield was a parent chaperone and is being remembered as a friend, mentor, and inspiration to others. >> it's definitely made us all hug each other and hold each other a lot. >> reporter: rehema ellis, nbc news. now to our nbc news e from the alec baldwin movie "rust" showing the actor handling and firing a gun during filming of a scene before the deadly shooting on set as chloe melas reports, if comes as he is potentially facing new charges. >> reporter: tonight, never-before-seen footage from the set of "rust" taken days before the shooting of cinematographer halyna hutchins. >> i don't want to shoot toward you. >> reporter: the clips obtained exclusively by nbc news show the actor preparing for scenes, firing weapons and interacting with crew members. >> i don't know why you're going up hills. you're going to break your [ bleep ] neck. >> reporter: according to a source familiar with the matter, these videos are among dozens provided to special prosecutors days before they announced plans to recharge baldwin with involuntary manslaughter. nbc news has not seen the rest of the videos. >> everyone who doesn't need to be in the path of the gun, can you please move? >> reporter: a portion of the evidence that could be presented before a new mexico grand jury starting tomorrow. tonight, baldwin's legal team and the prosecution declining to comment on the videos. since the incident baldwin has denied pulling the trigger. the movie's armorer, hannah gutierrez-reed, has pleaded not guilty to involuntary manslaughter charges. her trial set to be in february. >> the gun was supposed to be empty. i was told i was handed an empty gun. >> reporter: tonight with the possibility of new charges on the line, alec baldwin's legal troubles taking center stage as prosecutors bring the deadly incident back into the spotlight. chloe melas, nbc news, new york. in 60 seconds, eight teenagers are under arrest on suspicion of murder after a 17-year-old was beaten to death near a school and how police say the fight started next. nged for me. breztri gave me better breathing, symptom improvement, and reduced flare-ups. breztri won't replace a rescue inhaler for sudden breathing problems. it is not for asthma. tell your doctor if you have a heart condition or high blood pressure before taking it. don't take breztri more than prescribed. breztri may increase your risk of thrush, pneumonia, and osteoporosis. call your doctor if worsened breathing, chest pain, mouth or tongue swelling, problems urinating, vision changes, or eye pain occur. ask your doctor about breztri. back now with a brutal deadly attack on a teen in las vegas. now eight are facing murder charges, and police are looking for more. miguel almaguer has the details, and i have to warn you, the video is disturbing. >> reporter: investigators say the swarm of high school students punched, kicked, and stomped to death 17-year-old jonathan lewis using viral videos of the brutal beating, police say they've now identified eight of the victim's classmates arresting the suspects between 13 and 17 years old for murder. >> what you see in the video, though, is approximately ten subjects kicking, stomping, and punching our victim, jonathan, as he is on the ground not defending himself until the point where he becomes unconscious. >> reporter: left to die alone in this alleyway, a passer-by found him unresponsive rushing him to a nearby high school, the coroner listing his cause of death blunt force trauma homicide as police work to identify at least two other students. >> just an incredible young man who just loved life. >> reporter: lewis' father says his son was defending a smaller friend. >> it's just absolute lunacy. it looks like these kids have gone totally mad. >> reporter: police believe the fight was over stolen headphones and possibly a marijuana vape pen taken from the victim or his friends. the teens agreed to the back alley fight after school, a brawl they say that ended in murder. calling what happened here void of humanity tonight police say the teenage mob who pummeled a classmate to death could soon be charged as adults. miguel almaguer, nbc news. coming up, why some doctors are rethinking when to turn to surgery for one of the most common and painful sports injuries. that's next. s guy again... pops! ay son! ya got a little somethin' on yuh face. needed a quick shave. quick shave? respect the process! it ain't my dad's razor, dad, it's from gillettelabs. gillette...labs? gillette's ultimate shaving experience. this green bar releases trapped hairs from my face. gamechanga! while the flexdisc contours to it. lookin' smooth. feelin' even smoother. how 'bout hookin' me up with some gillettelabs? check your texts. you're the best. nah, you're the best. the best a man can get keeps getting bettuh. the next generation of shaving 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(♪♪) (♪♪) (♪♪) (♪♪) get exclusive offers on select new volvo models. contact your volvo retailer to learn more. a health alert for you tonight. it's a common and dreaded injury, but is surgery always the best way to repair a torn acl? liz kreutz with a surprising study. >> reporter: it happened to soccer legend megan rapinoe, nfl player daniel jones, even aspiring mixed martial arts fighter, mark zuckerberg. acl tears are one of the most common and debilitating injuries for both professional and recreational athletes, between 100,000 and 200,000 a year in the u.s. >> you can see it's completely torn. >> reporter: for years knee experts considered surgery the go-to option, but a recent study in "the british journal of sports medicine" found 90% of ruptured acls treated without surgery showed signs of healing three months later indicating nonsurgical treatment could be an effective alternative. >> what we have seen is people begin to question whether this should always be done. >> reporter: dr. bob sallis at kaiser permanente fontana medical center in california has seen firsthand the benefits of nonoperative treatment. >> it's not a perfect procedure and, in fact, we know that about one in three people who have their acl reconstructed have another acl subsequent injury, have another acl tear. >> reporter: that's what happened to dr. sallis' patient, who had the surgery 15 years ago. >> when you tore your acl, what options were you given? >> i was asked, do you feel the knee shift when you go up and down the stairs, and i said, yes, so i was not given options, i was recommended surgery. >> reporter: it took a year before sadie was back to playing competitive basketball. she still walks with a slight limp, then earlier this year, she tore that same acl. this time she opted against surgery. four months later with the help of a brace and physical therapy, she's back on the court. >> nonsurgery, i have to say, has been really nice. >> i'm just going to pull and push. >> reporter: dr. sallis says there are cases where surgery will be the best option, but that doctors shouldn't jump to the conclusion. >> if the larger medical system is set up to incentivize surgeries -- >> as a surgeon you make your money doing surgery, so most surgeons want to do surgery, and not just because they make money by doing it, but because they think, you know, it's the right thing to do. >> reporter: the knee he says may be more resilient than previously believed. liz kreutz, nbc news, fontana, california. next tonight, star to the youngest coach in division 1 athletics, her next championship win could be days away. i got the power of 3. i lowered my a1c, cv risk, and lost some weight. in studies, the majority of people reached an a1c under 7 and maintained it. i'm under 7. ozempic® lowers the risk of major cardiovascular events such as stroke, heart attack, or death in adults also with known heart disease. i'm lowering my risk. adults lost up to 14 pounds. i lost some weight. ozempic® isn't for people with type 1 diabetes. don't share needles or pens, or reuse needles. don't take ozempic® if you or your family ever had medullary thyroid cancer, or have multiple endocrine neoplasia syndrome type 2, or if allergic to it. stop ozempic® and get medical help right away if you get a lump or swelling in your neck, severe stomach pain, or an allergic reaction. serious side effects may include pancreatitis. gallbladder problems may occur. tell your provider about vision problems or changes. taking ozempic® with a sulfonylurea or insulin may increase low blood sugar risk. side effects like nausea, vomiting, and diarrhea may lead to dehydration, which may worsen kidney problems. living with type 2 diabetes? ask about the power of 3 with ozempic®. 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