From nbc news World Headquarters in new york this is nbc nightly news. Reporting tonight, erica hill. Good evening on this Independence Day. As americans across the country celebrate the nations 239th birthday authorities are focused on an unseen threat one that had them all on heightened alert. While there is added security around the holidays may feel like your new normal it is raising concern. We begin with a look at how cities across the country are responding. Nbcs ron mott starts us off. Good evening. Reporter erica, good evening. Especially in the larger cities security is tight, hightech. They are deploys radiation and detection equipment, for example. Officials tell nbc news, a lot of enhanced security will not be visible. Around america this fourth of july authorities are on heightened alert. Added fire power from new york to boston to maintain street. Barricades and check points at the national mall. In the countrys largest city a neverending terror target 7,000 police on patrol. We have not any specific information at this time about any threat directed specifically at new york. But we have become increasingly concerned, as youre aware, over the last couple of months that the threat isis is constantly trying to urge r encourage. Reporter Central Command of a floating Law Enforcement fleet numbering 50 vessels today. Months of planning go into safeguarding new york city. The boat traffic coming in for all the big fireworks traffic tonight. Captain gordon is commander of the port of new york and new jersey. Theres going to be thousands of boats out here for the Fireworks Show. Were just looking for anything out of the ordinary. Reporter tourists are ready. I want to take in what i can, be around of my surroundings and not put myself out there. Im not worried about it. Were going to have fun with the family. Reporter security aside, patriotism was front and center. I hereby declare reporter 100 of americas newest citizens took the oath at mt. Vernon and got a special welcome from cia director john brennan. Today, you are just as american as the neighbor who was born in the united states. Reporter young and old turned out in edmond oklahoma waving flags. And drum beat marking freedom in all of her colorful glory. Police commissioner bratton says this is the largest detail deployed for the fourth of july. Federal officials tell nbc news that while theyre very confident about the security measures in place, they remain vigilant. Kristen welker is at the white house. Good evening reporter erica, good evening. Top Law Enforcement officials have been in contact with state and local officials throughout the day. They say they are confident with the security measures in place in cities across the country. Tonight they emphasize there is no specific or credible threat. Instead, top officials are concerned about the uptick in chatter online in recent weeks, with isis calling for attacks at nation celebrates Independence Day. Now, some messages have urged isis followers to strike where you are. Adding to those jitters, isislinked attacks, including the one in tunisia, which claimed 38 lives, mostly in british tourists. We have seen an uptick at home. Now, one of the biggest concerns socalled lone wolf attacks that are harder to track. Intelligence Officials Say this type of readiness could be the new normal as isis attempts to recruit on social media. The mention tonight for americans,en enjoy the holiday. If something seems out of place, dont hesitate to report it. Nine people are recovering after a Fireworks Show took a turn for the worse. A malfunction caused two or three fireworks to explode is into the crowd on of about 20,000 people. All nine victims were treated and released. The exact cause is under investigation. More than a half dozen president ial candidates are seizing the opportunity to campaign on this holiday weekend. Working the crowds and meeting with voters in the early primary states of New Hampshire and iowa. Nbcs Kelly Odonnell is on the trail tonight in gorham New Hampshire. Good evening. Reporter good evening, erica. Like fire woks and hot dogs campaigning on the fourth of july is political tradition. It gives candidates patriotic imagery and access to a large number of voters. But that can also include protesters and competing for elbow room with other candidates. Summer fun in New Hampshire. Means the working holiday for the candidates of 2016. So many contenders here on the same day. Among the republicans, marco rubio. Hurry up. We need your vote. Reporter a newly announced candidate. Chris christie spent five Straight Days here. I love this. Reporter add mitt romney to the mix in gop elder statesman. For voters it may be too much to take in. I think they should spread out a little bit more. If you have four or five here i would like to go check them all out. Reporter and rick perry baby kissing for a canine. And jeb bush managed expectations. Were making slow progress. Im the tortoise in the race. Reporter in north country, motorcycle engines revved up the parade route. So did democratic frontrunner hillary clinton. This road has been used to keep people moving to keep that pace. Clinton staffers said the rope made it easier for clinton to be seen by voters and supporters. A small but Persistent Group of protesters repeatedly shouted at her along the way. Clinton walked a milelong distance reluctant to discuss her detractors. Does it rattle you all . I love parades. We have had such a great response. A lot of energy to celebrate the fourth of july. Reporter and clintons most insurgent democratic rival is bernie sanders. He spent his time in iowa. Donald trump has been talked a lot about a lot here. He was not on the campaign trail. He has not been seen in public since his controversial remarks about illegal immigrants. Romney and bush and rubio and christie have denounced those. Trump has no Public Events on his schedule for the next few days. Erica . Republican candidate ted cruz will be a guest tomorrow on meet the press. Tonight the shooting death of a Young California woman is also drawing attention to immigration. Several Officials Say her alleged attacker had been deported from the u. S. Five times. Nbcs joe fryer has that story. Reporter while walking along San Franciscos popular pier Kathryn Steinle was shot and killed with her father by her side. There was a pop and kate went down. Reporter it appears to be random. Officers arrested frances kuo sanchez, 7 felonies 4 for narcotics. He had already been deported five times and should have been in custody again. It would have been so much better of course if he were gone and they would have done what they should have done. Reporter earlier this year sanchez was in the the custody of i. C. E. In march, he was turned over to San Francisco county jail for outstanding drug charge. A charge that was eventually dropped. Immigration assets asked to be notified when sanchez was released but San Francisco does not grant such requests. The city policy city law is very clear that we dont honor i. C. E. Detainment. Reporter San Francisco officials reportedly say i. C. E. Could have issued a warrant or obtained a court order to keep sanchez in custody. It is a divisive debate on policies in the wake of steinles murder. Were not dwelling on that. Justice will reign hopefully with that. Its not going to bring kate back reporter joe fryer, nbc news los angeles. Moving overseas where all eyes are on the referendum in greece. It is just hours away. It could rescue the country from financial collapse. There is so much at stake that the countrys finance minister accused creditors of terrorizing greece into more austerity. Reporter in hours polls will open for a vote that could change the future of europe. Greeks will decide whether to accept the measures europe is demanding. Last night, thousands from both sides filled the streets. The Prime Minister was among them. Calling on greeks to vote no to europes demands. Others say the country must vote yes. It will face political and financial isolation. For many it seems an impossible choice. This weekend, there were more lines outside atms and the tourist industry is seeing a massive drop in books. Greece is on the brink of economic collapse. Aid organizations are preparing to step in to help the greek people in the weeks ahead. Erica . Keir thank you. This fourth of july will sound a bit different for many in the west tonight. Thats because the signature fireworks booms are silenced. Authorities saying it is just too dry. And the chance of a wandering spark triggering another fire is simply too great. Jacob rsa a rascon has our report. Reporter americans always celebrate with a spectacular display. A single spark can trigger a massive inferno, many have decided fireworks arent worth the fire risk. In california i have never seen it this low, actually. Reporter a wildfire recently destroyed 30 homes. The Fireworks Show has been replaced with a laser show. Probably will be choreographed to music. Lots of lights and colors. It should be something exciting and new. Reporter other shows have been canceled due to the drought from oregon to montana. Its not a great thing. We definitely dont need anymore fires reporter the owner of pyrospectacular, one of the oldest and largest fireworks in the country, said professionals are prepared for the extra danger. We got ahead of this 60 days ahead of schedule. We had training seminars for fire service personnel, brought them out, did demonstrations reporter dozens of communities across the west are banning all personal fireworks. In washington fire officials demonstrate how quickly a smile firework can ignite dry brush. Look at that. Reporter here the governor isnt taking any chances after a rash of wildfires, strongly urging his state to skip the explosions. Okay. 222. 24. Reporter not everyone is listening. We have lines of people around here. It gets crazy. Reporter a region ready to burn holding its breath for an Independence Day free from further disaster. When nightly news continues on this saturday the Ripple Effect of shark attacks off the coast of North Carolina. And the night of the living deadheads this weekend in put your hand over your heart. Is it beating . Good then my nutrition heart health mix is for you. Its a wholesome blend of peanuts, pecans and other delicious nuts specially mixed for people with hearts. I said people with hearts. Because Hearts Health is important. Thats why ive researched optimized and packaged this mix just for you. Not you. 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But thats not the only industry feeling threatened. We have more tonight from gabe tkpwaou tear easy reporter the outer banks has never seen a summer quite like this. You have been coming here more than 30 years on vacation. And this year is the first year you dont want to go in the water. Absolutely. Thats right. This is the first year. Reporter seven shark attacks in North Carolina in just three weeks. Vacationers on edge after scenes like this. Two men fish anything Kill Devil Hills reeled in a six and a half foot shark before releasing it back into the water. Beach patrol out in force today but posted shark warnings few and far between. I think every year when you come down here it is certainly a consideration. After all they do live out in that water reporter why this years shark surge . We went from water temperatures in the mid70s to water temperatures in the mid to high 80s in the span of five days. What that may have done is caused all the sharks that are part of that migration to move up as one big mass. Reporter the predators arent just threatening tourists theyre threatening livelihoods. Local fishermen say the sharks are ruining their catches. You can look and theres three, four eight, nine sharks because they know youre going to hook a tuna and then the dinner bells will ring. Reporter glen hopkins has been fishing 35 years but he has never seen this many partially eaten fish. You have the tuna right there. All of a sudden out of nowhere, the shark comes up and grabs the whole thing. I would say last month, probably 25,000 out of my pocket thats gone into the sharks bellies reporter tonight these communities are wondering if the attacks are over or whether theres still anything lurking too close to shore. Gabe gutierrez, nbc news,rodanthe, North Carolina. Around the world in a if youre taking multiple medications does your mouth often feel dry . 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And visit our website to learn how you may be able to get every month free. There is no denying the catch of the day at a very wet game last night in washington between the nationals and the giants. You can see the wet bat in this video as it slipped out of the batters hand flies into the stands. Luckily, look at that this man catches it. Almost making it look too easy. Rewarded for his efforts, a kiss on the cheek, as you saw, a hardy round of applause. Two pilots are hoping their solarpowered plane changes the way we all look at energy and efficiency. They are flying around the World Without any fuel landing in hawaii yesterday on the most recent leg of that mission. But as nbcs Hallie Jackson tells us the historic flight is really just the beginning reporter after it crosses the u. S. In the next few weeks, this solarpowered plane will have just two flights left before it finishes it roundtheworld trip. And thats when the real journey begins. We want to compete around the world. But the challenge for us is to give the message that we have this airplane reporter that message is this plane can fly 22,000 miles without any fuel. Imagine what else clean energy can do. This is what drives us. Reporter it is why they have spent 12 years on solar impulse. Designing it to squeeze every drop of energy out of the sun efficiently. Each of the solar cells is only the width of a single hair. 17,000 of them lining the wings here which are longer than a 747. Even though the plane looks huge it weighs only as much as a car. The electric motors are three times more efficient. If this Technology Works in the air, why not on the ground . People might say, well this is a stunt. This is one off. Ill never fly in a solar plane in my lifetime. What do you say to those critics . Its not good for people to believe that. It is also pioneering for Energy Efficiency for Clean Technology for energy saving. Because this is the next step reporter their flight is about halfway over. But their mission is just getting off the ground. Hallie jackson, nbc news, owe oahu oahu. From solar power to lightning power. Check out cinderellas castle during an epic thunderstorm last night. Tourists captured Mother Nature unleashes branches of lightning. The happiest place on earth briefly in the eye of a spectacular storm. When we come back a psychedelic trip down memory lane with the grateful dead. Roundup im a loving husband and a real good dad but weeds just make me rattlesnake mad well roundup has a sharpshootin wand im sendin them weeds to the great beyond roundup yeha [ whip cracks ] t point and shoot hit em in the leaves, and it kills to the root round fences, trees even mulched beds cause the only good weed is a weed thats dead roundup yeha [ whip cracks ] [ male announcer ] roundup. [ whip cracks ] with a onetouch wand. This allergy season, will you be a sound sleeper, or a mouth breather. Well, put on a breathe right strip and instantly open your nose up to 38 more than allergy medicines alone. So you can breathe and sleep. Shut your mouth and sleep right. Breathe right. Theres a more enjoyable way to get your fiber. Try phillips fiber good gummies plus energy support. Its a new fiber supplement that helps support regularity and includes b vitamins to help convert food to energy. Mmmmm, these are good nice work, phillips the tasty side of fiber, from phillips. This weekend marks the end of a remarkable 50year run for the grateful dead. The legendary rock band is performing three fair thee well shows in chicago to fans packed of course with loyal deadheads. Years nbcs john yang. Reporter what a long, strange trip its been. Reporter this weekend the grateful dead said its the end of the road a half century after they began. Three soldout shows at chicagos soldier field. A sea of tie dye. This could be the last weekend for the famously dedicated fans known as deadheads. How many concerts have you been to . 320. 420 but thats a rough count. No show was alike. That was the bond with the band. Every night is going to be an experience that we are going to have together. Its a religious experience. If you get it you get it. If you dont, sorry. Its the best thing ever. Reporter for those who recall when the dead began in the 60s to those barely born when they last played in 1995 the year iconic front man jerry garcia died. John mayer and andy cohen were at a concert last night. And steve leaseman is a dead head. You dont have to look far down from people who went from flower power to real power. Reporter all making a pill grammage to bid fair thee well to the grateful dead. John yang chicago. That is nbc nightly news for this saturday. Im erica hill reporting for from the new york. Ill see you tomorrow morning on today. From all of us here at nbc hows it progressing with the prisoner . Hell tell us everything he knows very shortly, sir. As you were. Where were we . 13 serving 14 service if your boss stops by, you act like youre working. Its what you do. If you want to save fifteen percent or more on car insurance, you switch to geico. Its what you do. Channing tatum. George clooney. Charlize and amy, hi everybody. Im shaun robin sochbility Weekend Edition of access hollywood. Summer season officially here and that means the biggest and the best movies are in theaters. Returning favorite laugh out loud comedy. Bilge big action adventure and biopick and romance this summer has it all. We start with the film bringing a little magic back to the theet are. Get the dollar bill ready ladies because these guys can dance. I love this. Can i have both. Is that possible . Can i