US police in riot gear have raided Columbia University in New York and arrested pro-Palestinian protesters occupying one of its buildings.
Around 30 to 40 people have been removed from Hamilton Hall, according to police.
The raid came hours after New York City Mayor Eric Adams said the demonstration at the school "must end now".
He also claimed the demonstration had been infiltrated by "professional outside agitators".
University bosses said they called in the New York Police Department (NYPD) "to restore safety and order to our community."
Members of the New York Police Department load arrested protesters from Columbia University onto a bus after entering the campus, 30-4-24. Image: Associated Press / Alamy"We regret that protesters have chosen to escalate the situation through their actions," a university spokesman said.
"After the university learned overnight that Hamilton Hall had been occupied, vandalised and blockaded we were left with no choice.
"Columbia public safety personnel were forced out of the building and a member of our facilities team was threatened. We will not risk the safety of our community or the potential for further escalation."
The spokesman added: "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."
Members of the New York Police Department escort protesters from Columbia University after entering the campus, 30-4-24. Image: Associated Press / AlamyThe protest began when students barricaded the entrance of Hamilton Hall at Columbia's campus on Tuesday and unfurled a Palestinian flag out of a window.
Video footage showed protesters locking arms in front of the hall and carrying furniture and metal barricades to the building.
Those behind the protest said they had renamed the building 'Hind's Hall' in honour of Hind Rajab, a six-year-old girl killed in a strike on Gaza in February.
Students watch through their building door at Columbia University as members of the NYPD stand outside, 30-4-24. Image Sipa USA / AlamyDemonstrators said they had planned to remain at the hall until the university conceded to the Columbia University Apartheid Divest's (CUAD) three demands: divestment, financial transparency and amnesty.
"Columbia will be proud of these students in five years," said Sweda Polat, one of the student negotiators for CUAD.
She said students did not pose a danger and called on police to back down.
'Walk away'
Officers raided the campus on Tuesday night after university bosses wrote to New York City officials and the NYPD formally asking for assistance.
A large group of officers dressed in riot gear entered the campus late on Tuesday evening.
Officers were also seen entering the window of a university building using a police-branded ladder vehicle.
Earlier, New York Mayor Adams urged demonstrators to leave the site. "Walk away from this situation now and continue your advocacy through other means," he said.
Columbia University also threatened academic expulsions for students involved in the demonstration.
Wider protests
Protests at Columbia earlier this month kicked off demonstrations which have spread across US university campuses from California to Massachusetts.
Dozens of people were arrested on Monday during protests at universities in Texas, Utah, Virginia, and New Jersey.
Police moved to clear an encampment at Yale University in Connecticut on Tuesday morning but there were no immediate reports of arrests.
Earlier, US National Security Council spokesperson John Kirby said President Joe Biden believed students occupying buildings was "absolutely the wrong approach" and "not an example of peaceful protest".
Columbia University said access to its campus has been limited to students residing in residential buildings and employees who provide essential services.
Additional reporting: IRN
