Physician who treated prince in the days before he died. His onetime Medical Center saying he is no longer an employee. As Police Return to paisley park in search of more clues. And the rock. Surrounded by sharkinfested waters, alcatraz was once an island prison thought to be escape proof. One man has managed his way out, and hes on the loose today. Wednesday, may 11th, 2016. Announcer from nbc news, this is today with matt lauer and savannah guthrie, live from studio 1a in problem fellrockef. Good morning, everyone. Welcome to today on a wednesday morning. Al roker continues this tour of our National Parks. Exactly. Hes been to white sands, now were sending him to prison. Hes in front of alcatraz this morning. Hey, al. Hey, guys. Thats right, one of the most feared prisons in the world, from 1934 to 1963. Alcatraz federal penitentiary. Ten years later, 1973, becomes a National Park. Now, its just unbelievable to see how popular it is. Well have a complete tour coming up a little later. Guys . Al, see you in a little bit. We want to start with our top story. The breaking news in massachusetts, where authorities are investigating a stabbing rampage at a mall and a home near boston. Nbcs joe fryer has the latest on all this. Joe, what happened . Good morning, matt. Police are trying to figure out what drove a man to go on this wild stabbing spree. It started at a nearby home and ended here at the mall. In all, three people are dead, including the attacker. Reporter inside this shopping mall, a grizzly scene. Two people viciously stabbed, the attacker brought down by a bullet from an off duty sheriff deputys gun. If it hadnt have been for his heroic actions, there could have been more loss of life this evening. Reporter the suspect, arthur darosa, rammed a car into a Macys Department store before running into the Silver City Galleria mall, creating total chaos in massachusetts. After assaulting several people, he made his way to bertuccis. Grabbing a knife, darosa stabbed two victims, killing a 56yearold man. Witnesses ran for their lives. I was shopping. I didnt know what was going on, so everybody started running, including the macys employees. We started running. Reporter the attack, with no clear motive, began after darosa crashed a different car near a home a few miles from the mall. 270 myrick street and birch avenue for multiple stab victims. Reporter darosa stabbed two people inside the home. One of the victims, an 80yearold woman, later died from her wounds. Officials say the attack doesnt appear to be terror related. This morning, there are new questions about the suspects mental health. In a statement to nbc news, darosas cousin said he was feeling suicidal and admitted to a local hospital but released tuesday morning. They stated he was fine, but obviously wasnt. I believe if he was better evaluated, the situation may not have happened. The surviving victims were all take tonn to a hospital. Conditions havent been released. One of the stabbing victims suffered lifethreatening injuries. So far, officials havent identified the hero officer. Joe fryer, thank you so much. To the president race. Bernie sanders says he is in it to win it after defeating clinton by double digits in West Virginias primary. It did little to dent clintons lead in the delegate count. Presumptive republican nominee donald trump rolled to victory in West Virginia and nebraska, setting the stage for a key meeting on capitol hill tomorrow. In a moment, well talk to senator marco rubio, trumps former rival. Lets begin with hallie jackson. Good morning to you. Good morning. Donald trump is acknowledging those wins in West Virginia and nebraska, but he is already looking ahead. Not just to tomorrows key meetings here on the hill, but to who he may pick as his running mate. Trump now insisting he wont announce his pick up till the convention in july. Reporter usually quick with an insult calling him lying ted. Little marco. Crooked hillary. Reporter trump has only praise for paul ryan. Hes a good man, wants whats good for the party. Reporter the candidate is trying to smooth the path ahead of tomorrows meetings on capitol hill. Dont expect a kumbaya moment. Sources close to the House Speaker caution itll be a proce process. Saying, ryan wants to commit to conservative principles and to bringing republicans together. It was a very, very bitter, divisive primary. Itll take more than a week just to repair and unify this party. Reporter ryan down playing expectations, returning to capitol hill. So is ted cruz for the First Time Since dropping out. Ruling out a thirdparty run, but keeping his options open. If circumstances change, we will always assess changed circumstances. Reporter and withholding an endorsement of trump. There will be plenty of time for voters to make the determination who theyre going to support. Reporter despite big differences on policy, another former rival, marco rubio, says he will back trump. Seemingly begrudgingly. I dont want Hillary Clinton to win. I want to be supportive of the republican nominee. I signed a pledge saying i would do so. Reporter rubio dismissed talk of the vp job. Trump lists chris christie. I like chris a lot. Im not going to say ruling in or not. I would say that i have in mind five different people. I think theyre excellent. Reporter looking to november, Hillary Clinton clearly ready to take trump on. I am looking forward to debating donald trump come the fall. Reporter clinton now getting her strongest show of support yet from the white house. Vice President Joe Biden stopping short of an endorsement, but just barely. I feel confident that hillary will be the nominee, and i feel confident shell be the next president. From the white house now to capitol hill, where we expect to see from speaker ryan later today, ahead of the meetings with trump. And trump finds himself in a new controversy. While his Campaign Says it tried to get a prominent White Nationalist off its list of potential delegates in california, the secretary of States Office tells us, it is too late to do that. Hallie jackson on the hill for us, thank you. As we said, senator marco rubio joins us exclusively. Senator, nice to see you. Good morning. Morning. Let me see if i can clear something up. You have said youre going to uphold your pledge, the pledge you signed to support the eventual nominee of the republican party. That appears to be donald trump. But when pressed on one question, would you vote for donald trump, you didnt seem to be able to make yourself say yes, ill vote for him. Will you say that now . Well, i mean, obviously, this is the quandary everybody finds themselves in. At least who holds my perspective. On the one hand, the party nominated someone ill have differences with, on policy and how he conducted his campaign. On the other hand, the only other choice on the ballot is someone i have more policy di disagreements with. As a candidate, i signed a pledge. What does support mean . Will you stand on a tv show like this and say, im keeping my pledge, or does it mean youll go to the convention and speak on his behalf, or go in the booth and vote for him . Obviously as a voter in florida, support would be the ultimate way for the primary way people support candidates in this country. To vote for them. In terms of what i intend to do throughout the campaign, i would just say i think donald trump would be best served by having people working on his behalf, that agree with him on these policies and are enthusiastic about his campaign and enthusiastic with things he has stood for. My reservations about him have been clearly stated and unchanged. You were explicit during your campaign about concerns. You said he was an embarrassment. You were fearful at the prospect of his hand on the nuclear codes. You said he wasnt a republican, not a conservative, that hed lose to Hillary Clinton. Are you exalting that pledge, piece of paper, over the fears you say you still have for the country, with donald trump as the nominee . Sure. The only other choice then would be to vote for Hillary Clinton or abstain, both supportive of her. I have more policy differences with her and am more scared of her being in control of the government. I think its clear, that this is the position obviously, i didnt want us to be in. Donald trump wasnt my first choice. I ran for president and did the best i could. It didnt work out, and Republican Voters chose a different direction. I have to respect the result, even if im not the even though it is not necessarily the one i wanted. I think, clearly, youre describing here the quandary, choice, that millions of republicans not just me but millions of republicans across the country are trying to grapple with. It seems youre being loyal, and you should be applauded for that, sticking to the pledge, but youre going to be leaving the senate. You dont want to run for governor of florida in two years. Its possible for you to put politics aside and take a principled stand and say, everything i said during the campaign, i didnt believe. I cannot support this guy. First of all, everything i said during the campaign, i still believe. But what youre leaving out of that is, you have to make a choice. You dont have a choice anymore between 17 people or even 5. For voters in florida in november, the choice is going to be, if you want to legitimately vote to elect a president , itll be between Hillary Clinton and donald trump. Or abstaining. If i as a republican abstain or vote for Hillary Clinton, thats support for her. I am not going to support Hillary Clinton. To put it bluntly, senator rubio, do you want donald trump to win . Do you hope in your heart of heart to wins and assume the presidency . Look, again, all of the policy differences i have with him remain. All of the reservations i have about his campaign remain. I clearly didnt want us to be in the position we are today. I was a candidate for president who tried to be the nominee myself. It didnt work out. I dont want Hillary Clinton to win. Donald trump is the only other choice on the ballot. I recognize that. I have a pledge to support the nominee on top of it. I intend to keep it. What i dont intend to do is spend the next six months taking shots at donald. Whether we like it or not, hes earned the right to make his case to the american people. He earned it at the ballot box, and ill respect that. Senator marco rubio, nice to spend time with us this morning. We appreciate it. Thank you. Thank you. Tomorrow on today, former Vice President dan quayle speaking out about the race when he joins us in studio 1a. Another round of tornadoes. This one causing significant damage in mayfield, kentucky. Gabe gutierrez is following it. The cleanup effort in oklahoma is in full swing. This as the states governor declared states of emergency in 15 counties. All this as millions more throughout the country are preparing for yet another round of potentially severe thunderstorms later today. Reporter this morning, western kentucky is cleaning up after two tornadoes touched down. One of them sending residents in mayfield running for cover. We heard loud noises and the glass crashing. We dove into the washroom and stayed there until the noises stopped. Reporter homes leveled, trees toppled, lives shattered. You could hear it. It sounded like it was right over the building. Reporter today, seven states are on high alert for more potential Severe Weather, after this weeks string of ferocious tornadoes. Oh, god reporter oklahomas governor declaring a state of emergency in 15 counties. Two people were killed. Please dont hit that barn. Oh, my god. Reporter the National Weather service saying this twister near wynnewood topped 136 Miles Per Hour winds. For jamie ramirez, the search for her lost pets was frantic. Now the harsh realization that her home is gone. Devastating. Reporter that devastation extending this morning to kentucky, where driscoll rushed to her friends house, only to find it in pieces. When i walked up, i started crying. I mean, its heartbreaking. No deaths were reported in the kentucky tornado. At least ten people were injured. Now today, a lot of people are bracing for the potential of Severe Weather. The swath of the country extends from north texas up through the midwe midwest. Right now, there are reports of flooding underway in tennessee, just north of nashville. Matt and savannah . Tough times there. Gabe gutierrez, thank you. Some of the video out of that region the last couple days is horrifying, and our thoughts are with the people there. Several new twists in the investigation into princes death. Authorities were back at his home last night, and a minnesota doctor who wrote prescriptions for the pop star has been identified. Stephanie gosk has the latest on that. Good morning. It had been quiet here the last couple weeks at paisley park, until late yesterday when a line of police vehicles, about a dozen or so investigators, entered the compound. It happened after a warrant for princes medical records was released publicly, showing that the pop star had been getting medical treatment here in minnesota from a local doctor. Up until the day before he died. Reporter according to a search warrant, a minneapolis area doctor was at princes home to deliver test results the morning he died. Dr. Michael todd shillingberg, seen in this video made for a local university, examined prince twice. Once on april 7th, before princes plane made an Emergency Landing in illinois. Whats the nature of the emergency . Unresponsive passenger. Reporter and again on april 20th, the day before he died. According to the warrant, the doctor told police he prescribed medications for prince, and the unspecified prescriptions were filled at a walgreenwalgreens. Investigators interviewed dr. Shillie shillenberg and caught sought records related to it at a Medical Center. The doctor says he works with north memorial clinic. That hospital says he is no longer an employee there. The doctors lawyer is not comme commenting. Late tuesday, police were seen at princes paisley park home. The sheriff tweeting, detectives were revisiting the scene as a component of a complete investigation. Offering no further details. The warrant does not say what the medications were that prince was prescribed or whether he took them. The toxicology report could shed some light on that. Its still not complete, and theres still no official cause of death. Stephanie, thank you very much. First test of Futuristic Technology that could revolutionize transportation is happening in nevada. The hyperloop. This was proposed by elon musk. Gadi schwartz is in las vegas. This is the first public test of the technology. Good morning, savannah. This right here is Hyperloop One. The idea eventually is to put people, to put cargo, in specialized pods, and then put them in airtight tubes like this and shoot them for hundreds of miles, all at the speed of sound. To put this in perspective, l. A. To San Francisco takes six to seven hours. This would take 30 minutes. Reporter faster than a speeding bullet train. More powerful than an airplane. Thats what elon musk was hoping for when he unveiled his idea for the hyperloop in 2014, sparking a Competition Among firms to build the first working model. The first version will be unveiled in the las vegas desert. Hyperloop is immediate, safe, efficient and sustainable. Reporter it is presenting a 10foot long sled, reaching 250 Miles Per Hour in two seconds. Well do this well and take the design, build two kilometers worth of it, and accelerate a vehicle ten times heavier, to a speed twice as high. End of the year, well do the kitty hawk moment and hit the fullscale loop. Itll handle a cargo of people. Reporter some speck keptics it impractical. Elon musk isnt associated with any specific company, but he has a contest among College Students to design and build a hyperloop pod. All players in a race to zoom us into the future of travel. If this test is successful, Hyperloop One might be in the lead. We believe were the one company that is actually pild g i building this, not just talking about it. Were showing it today with the live test of our propulsion system. In a few hours, Hyperloop One promising to unveil the Technology Thatll make all of this work. There is a lot of excitement. Still a lot of skepticism. One big question, what to do in an earthquake. Matt and savannah, back to you. We have so many questions, gadi, but its exciting to see. Thank you. Let us head back to al in San Francisco for a check of the weather before his big tour of the National Parks. Al . Thats right, guys. Weve got a lot of Severe Weather going on. Stretching from the plains all the way into the Mississippi River valley. Look on the radar. You can see our nbc affiliate is reporting a lot of flooding going on in that area right now. We have a risk of Severe Weather today, stretching from san angelo all the way to des moines. 23 Million People at risk. Large hail, isolated tornadoes are possible. This system will be pushing through, bringing heavy rain from chicago all the way down into texas. As it pushes through, it will leave a lot of rain behind it. Damaging winds and the possibility of those isolated tornadoes, as well. Not as strong as