An officer accidentally discharged his gun as the New York Police Department worked to clear Hamilton Hall -- a building that had been occupied by Columbia University students on April 30, Assistant Chief Carlos Valdez, the commanding officer of the NYPD Emergency Service Unit, said Friday.

During the operation, a sergeant unintentionally discharged his firearm while attempting to gain access to an office.

"The sergeant was transitioning his firearm to his non-dominant hand to unlock the office door from the inside when the discharge occurred," Valdez said.

There were no injuries and the bullet was contained within the vacant office. Valdes said that at no point were police officers, members of the public or protesters in danger.

"This was purely unintentional," he said.

New York University and New School, in separate statements, said they requested police move students from their campuses after multiple rounds of negotiations failed.

NYU said the "encampment had become increasingly untenable for the NYU community and the neighborhood we inhabit." Classes will proceed as normal today.

NYU said it is aware of calls for a 4 p.m. protest at the former site of the encampment.

The New School, which switched to remote learning Friday, said students continued to set up in the lobby of the University Center building and block access to the "residence hall, classrooms, library, and cafeteria."

Despite the university "pleading to allow their fellow students to enter their residence hall, the protesters would not budge."

The New School said the protests continued even after they "provided a confirmed date this month for the Investment Committee to consider a vote on disinvestment."

"It is a sad day for all of us who are part of this university community and who believe in free speech, which we have pledged to protect and will continue to protect," The New School said in a statement.

Fifty-six people have been arrested at The New School and New York University after the schools authorized police to clear encampments, according to the New York Police Department.

Forty-three people were arrested at The New School and 13 people where arrested at NYU, the NYPD said.

-ABC News' Aaron Katersky

NYU has requested assistance from the NYPD to "disperse the illegal encampment on their property."

"As per their request, we are on site and our officers will be assisting with the unparalleled professionalism embodied by our police officers," NYPD Deputy Commissioner, Operations Kaz Daughtry, said in a statement on social media.

The University of Minnesota has reached an agreement to end the student-led encampment on campus.

The university will reopen previously closed buildings and the student coalition has pledged not to organize disruptions during final exams and the commencement ceremony.

Representatives of the student coalition will be given the opportunity to address the Board of Regents at its May 10 meeting over its call for a divestment, students will receive amnesty for their encampment, and the university will also explore an affiliation with Palestinian universities, hosting scholars at risk.

"Our meetings have been grounded in listening, learning, and respect, and I believe they were a very positive first step in reaching mutual understanding. Though the original meeting was scheduled for 30 minutes yesterday, we engaged in constructive conversation for more than 90 minutes. We then met two more times to discuss the proposed agreements," University of Minnesota interim President Jeff Ettinger said in a statement.

"We regret that these meetings did not happen sooner, and have committed to regular meetings moving forward to continue to discuss this coalition’s concerns," Ettinger said.

Ettinger also highlighted that the university supports freedom of expression as a fundamental part of its mission.

"While we do not condone tactics that are outside of our policies, we appreciate student leaders’ willingness to engage in dialogue. I value the challenging and healthy conversations we’ve had," Ettinger said.