STORY: ESU's commander Carlos Valdez: "Well, we had individuals that were barricaded at a location..."

The New York City Police Department on Friday defended its dramatic operation earlier this week clearing pro-Palestinian activists occupying a part of Columbia University.

Officers from the NYPD's Emergency Services Unit, or ESU, were seen using a ladder to breach the building Tuesday night.

The raid resulted in dozens of arrests. Additionally, police said one officer accidentally fired his weapon. No one was injured.

ESU's commander Carlos Valdez said the unintentional discharge occurred when an officer moved his firearm from one hand to another while trying to open a door.

"The bullet traveled through the glass and into the office they were trying to gain access to."

Tuesday's operation was one of several by police departments on protest encampments on college campuses across the U.S. over the last week.

This footage shows a protester with a shield running from police at Portland State University on Thursday.

"I'm a student here, I'm an English major..."

This student was arrested at UCLA in the early hours of Thursday when police cleared demonstrators.

The demonstrations roiling colleges are a response to what activists see as a brutal Israeli operation against Palestinians in the Gaza Strip, and what pro-Palestinian activists characterize as U.S. support for Israel.

Jewish students on campuses have said the anti-Israel demonstrations have included incidents of harassment and antisemitism.

U.S. President Joe Biden: "There's the right to protest, but not the right to cause chaos."

Responding to the campus crisis, U.S. President Joe Biden on Thursday said violence and vandalism were not protected forms of political expression.

"As president, I will always defend free speech, and I will always be just as strong in standing up for the rule of law."

But what can seem like heavy-handed police raids may have further galvanized student outrage.

Columbia student Oishika Neogi: "The police were aggressive and I think that is important to note."

Oishika Neogi is a student at Columbia's Graduate School of Journalism who witnessed Tuesday's raid.

"Irrespective of anything, I think conversations could have been had before the police were called in, and such a large number of police. That is just a different environment altogether."

The NYPD said on Friday police arrested another 57 protesters after clearing encampments at New York University, and the New School.