Been underway for several days. Just after 9 00 p. M. Eastern the new York City Police department breached Hamilton Hall using a truck with a ramp. That happened almost 24 hours after protesters broke into the building and occupied it. The nypd says Hamilton Hall is now cleared and so is the Tent Encampment on the south lawn of the campus. An nypd spokesperson spoke to nbc news shortly after the officers went in. The building was very heavily fortified. Doorways were blocked by Soda Machines, couches, plywood. So there were rumors that the nypd used tear gas. The nypd does not use tear gas. We use a Distraction Device. It is a device that is thrown and makes a loud bang. A stun grenade. It is a Distraction Device that makes a loud noise. That allowed officers time to get through the barricades. Columbia university formally requested Law Enforcement help earlier this evening. The weeks long negotiation broke down. Columbia released a statement saying the following. Quote, the decision to reach out to the nypd was in response to the actions of the protesters, not the cause they are championing. We have made it clear that the life of campus cannot be endlessly interrupted by protesters who violate the rules and the law. Nbc news correspondent Antonia Hylton has been covering the protests and joins us now. Tell us what is going on there. You have been there for hours. Reporter a, it has been a pretty unbelievable scene. Although right now what you are sitting behind me is the aftermath. We now know from the nypd there have been 100 arrest, 40 of them in Hamilton Hall, the building behind me that protesters have been in, about 60 of them since last night. What we know from students is there is a mix of Student Organizers who have been part of different groups and movements, but also the nypd saying there are outside agitators, anarchists, people who have no affiliation with columbia who were leading and part of this movement into Hamilton Hall. We saw at least two buses full of protesters leaving the scene and now the nypd is saying that most of this operation is over, but we are still hearing from students, steph. Students were not part of the protest, by the way, who say they are barricaded by officers in their dorm rooms. They sent photographs and we could see officers making it impossible for students to move around campus, even if they were clearly identified as not being part of any action or protest. Everyone on all sides of this issue from jewish students who have long felt unsafe on campus, to propalestinian students who felt free speech has been maligned by the university, to Faculty Members on all sides and all kinds of disciplines. There is immense anger right now. This feeling that it did not have to escalate to this point. That negotiations couldve gone better. An example that keeps coming up today is brown university. Brown had an encampment and now it is over. It has been packed up, why . Because the university had a dialogue with the students and decided they would bring questions about Investment Holdings to a board of governors vote so the university is at least going to look at the claims and concerns of the students involved. That is not to say they will take the actions the students demand, but at least they are recognizing it through a democratic process. An olive branch that couldve been offered. This will now be the second time the nypd has entered. Students of watched friends and classmates get arrested, boarded on buses. They describe it as incredibly traumatizing. Everyone i talk to says they expect to wake up tomorrow, still shaken by all of this, because we heard in a letter from the columbia president explaining the decision to bring the nypd and, that they plan to have an nypd presence past graduation. Graduation is may 15. They want officers here until may 17. That is not making most of the students i talked to feel safer. It is making them feel more on edge and there is more concern, now than ever, that this moment that is supposed to be a happy time when people come in from All Over The World to celebrate and get ready for graduation, that there is really no way it is going to feel like business and usual for them. A lot of people are in pain and incredibly frustrated right now. They are in pain because the police are there or in pain because of the prolonged protest . Which one is it . Reporter it is both. For many of the students, especially in the undergraduate body, there is anger at the nypd. Even students who were not part of the Protest Movement to are not necessarily propalestinian, describe the sight of seeing nypd enter on april 18 as traumatizing. Really difficult to see people they see in class so they know and like and do activities with, getting zip tied and facing court summonses. That is not something that made them happy. Then for jewish students who said they felt targeted and dealt with harassment, seeing antisemitic signs and people protesting from all over new york, coming because the cameras are here and they could get attention and their 15 seconds of fame, that that has been really traumatizing for them as well. That is one thing people here can agree on, this feeling that the administration has failed everyone on all sides. You hear it from the students, you feel it from faculty and staff. That at some point the leadership here failed to figure out a way to make everyone feel heard and feel safe. That there shouldve been a middle point, because other schools, other communities seemed to be able to find more peaceful ways to get this done. Now here is the second time the nypd has entered. Another 100 or so people are on their way downtown to face charges and court summons. It is not making anyone happy. I have yet to meet a Single Person rejoicing about this or who feel settled or safe at the moment. That is for different interpretations, but that is one thing people seem to be able to come in the middle on. Just looking at it, such an upsetting scene to see on a college campus. The students are these protesters, i am not sure if they are all students, have they broken the law . Reporter well according to the nypd, the people who entered Hamilton Hall absolutely did. They are Planning Trespassing and other charges. Minor felonies so the students involved in that could be facing very serious legal consequences. We know from the university that they plan to expel students inside Hamilton Hall and part of the breach last night, but we also know there is a possibility that there are these outside actors who may be facing serious charges, but may have nothing to do with columbia at all. That is unsettling for students on all sides, hearing there maybe this element on campus. People they dont know, have any familiarity or access to, that they may have been co opting in a way what has otherwise been, day after day, a fairly peaceful protest. Most of what we have seen in terms of the encampment and the actions theyve done there. The students built a library. They invited faculty to give talks in the encampment. This has been peaceful and there is a feeling even from the propalestinian students who were advocating for students to have their voices heard and to continue the process, there is this feeling that things have gone really far, who is responsible for this and how did this campus get out of control . How much has this taken over campus life . Our classes still going on . Reporter no, there were virtual options today. Students are literally, right now, barricaded into their dorm rooms. They cant even walk to go get themselves food. Student reporters trying to access the studio in which they broadcast their radio shows or meet with each other, they are reporting they cant even get into spaces they typically have complete ownership over. That is how locked down things have been. Night after night there have been protests on the street. People have been in public having their voices heard, but tonight, a very large public protest behind me here was dispersed. An Audio Message from the nypd went out making it clear that anyone who stayed near as they got ready to move in was going to be risking arrest. So what we had was hundreds of people on every side pushing in front of businesses, Residential Homes and apartment buildings, screaming shame on you. Screaming at the nypd all night and refusing to leave this space. We saw, around the corner, another corner of campus, that some of the people out on the street were even part of those arrested this evening. Those numbers, that is reflective of a much larger, chaotic scene on campus. Only about 40 of those people are confirmed to be actual protesters in the hall itself. My goodness. Antonia hylton, thank you for being there. Im glad you are safe. I want to bring in carmen best, retired Seattle Police chief. A former member of obamas task force on 21stcentury policing and former Public Safety director for dekalb county, georgia. Both are msnbc Law Enforcement analyst. And former Hostage Negotiator jim kavanaugh. Help us out. Obviously we could not see what was happening inside that building. Could you give us an idea of what police were doing . From all indication i think we probably can do a little Deductive Reasoning and make some real good prediction or assumptions in terms of their approach. Once they were inside im quite sure they were looking for those who were involved in overtaking that building. A couple dozen or so and i am quite sure they went through each floor of that building, as well, too, to make sure that building was secure. So i think we should all be very thankful for the fact that it appears to have ended tonight without incident, but they enter into that building and we saw it from the ground and they went upstairs, as well, through some elevation. But it appeared to have secured the scene safely for everyone and without incident. Chief best, as you look at the video tonight, what stands out to you about how the nypd is responding . Well, i felt a lot of empathy for everyone involved. This is reminiscent of the protest post george floyd in 2020 where several people occupied in seattle with 10 send a lot of the chaos that went on there. Look, at some point while you want to protect everyones first amendment, free speech. I sent two daughters away to college and i can only imagine what the parents of those students who are, in many ways being threatened or feel unsafe at school, how they are feeling about their children. No officer, myself included when i was an officer, wants to take young people to jail, but there does have to come a point where there does have to be effective rule of law and it cannot be chaos and pandemonium. So in some instances, while these are not pleasant for anybody, you know, action needs to be taken. As you can see the officers are being slow, methodical, and trying to take the students out that they have to arrest and removed from the scene. Jim, i know i am asking you to make a best guess, but from a police standpoint, why move in now at 9 00 at night . Especially when columbia said it made the decision to make this a Law Enforcement matter early this morning. Well, the nypd has to gather forces. They have to make a strategic plan. You saw that they brought out a phalanx of officers. They secured the area around the building in question that was seized by the protesters. They brought in the Emergency Service unit and the vehicle with a hydraulic ramp. They bypassed the barricade on the first floor that protesters had probably barricaded all of the entrances. The Intelligence Officers knew that. He used the vehicle to enter the second floor. They put a whole lot of officers in there to bypass the barricades and make the arrests and work up the floors to the top floor, which was kind of the Control Center of the protesters. And they fought through some barricades there, they described, and turned over Soda Machines and couches and so forth and made the arrests. Then they went out and took down the tent city that was in the grassy area. So a very good strategic plan. Very methodical, very professional. This is how we want Americas Police to look. This is how we want them to act. Now we also support free speech and the students voices are heard. They have been on the news for a week or more, but breaking into buildings, breaking windows, threatening to burn the buildings down, you know, this is burglary and Breaking And Entering and threats of arson. You know, the police have to get their plan and move. There is no great timing to it. It is not a residence, per se, and people know they are coming. At night, as you know, being a new York Resident it is kind of free of traffic around that time, so it could be a good time rather than clogging up all the streets. So i think the nypd gets an a on this and we did see, by the way, in closing, the other day when lapd brought out their special unit and did the same thing. An overwhelming show of officers. They peacefully surrounded, carefully, slowly, the encampment of the officers the protesters on the quad and one by one they arrested, one at a time, and walked them to the police vans. Very slow and did a great job. That was lapd the other day. This is nypd today. So i think this is a very good example of how we have to do this. Now protesters, you know its going to go on, but as long as the violence and danger is gone for a while, that is what they are paid to do, so i give them an a . They call them Law Enforcement because it is their job to enforce the law. How do they deal with this mix that supposedly there are outside agitators and this is a Campus Building Met building meant for students . We have seen a number of these types in recent years. Following the death of george floyd and even at columbia where you have outside sources who are not affiliated with the city, with the university, and their job often times, solely, is to continue this type of unrest in those communities. They have to be dealt with specifically and i am quite sure they will be identified. Some of them may have history of doing this. Some of them this may be the first time they have been involved in these types of incidents, but they are right they are identified. Nypd has already indicated they are certain there have been individuals from outside the city, outside the University Community who were involved in keeping this unrest going. All right, thank you all so much. I appreciate you helping us out tonight. We will stay on top of this Breaking News at Columbia University, but we also want to get to the other big story of the day. When we return we are breaking down Donald Trumps intent stay in the courtroom. A key witness takes the stand as the former president gets in big trouble for violating his gag order. The 11th hour just getting underway on a very busy tuesday night here in new york city. Tech does your windshield have a crack . Trust safelite. This customer had auto glass damage, but he was busy working from home. So he scheduled with safelite in just a few clicks. We came to his house. 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