NEW YORK: Dozens of helmeted police flooded Columbia University's campus in the heart of New York City on Tuesday to evict a building occupied by pro-Palestinian student protesters and detain demonstrators.

Police climbed into Hamilton Hall via a second floor window they reached from a laddered truck, before leading handcuffed students out of the building into police vans.

The hall had been occupied at dawn by demonstrators who vowed they would fight any eviction, as they protested the soaring death toll from Israel's war with Hamas in the Gaza Strip.

The action came as university administrators around the United States have struggled for weeks to contain pro-Palestinian demonstrations on dozens of campuses.

In a letter addressed to the New York Police department, Columbia University president Minouche Shafik said that the occupation of the school building was being led by “individuals who are not affiliated with the University” and asked “NYPD’s help to clear all individuals from Hamilton Hall and all campus encampments.”

She also asked the police to remain on campus through at least May 17, “to ensure encampments are not reestablished.”

Writing on Instagram, the protests slammed Shafik’s statement, saying “her use of the words ‘care’ and ‘safety’ are nothing short of horrifying.”

The weeks of demonstrations -- the most sweeping and prolonged unrest to rock US college campuses since the Vietnam war protests of the 1960s and 70s -- have already led to several hundred arrests of students and other activists.

Many of them have vowed to maintain their actions despite suspensions and threats of expulsion.

Earlier, protesters at Columbia were seen using ropes to hoist crates of supplies up to the building's second floor, apparently signaling the students had planned to hunker down.

President Joe Biden’s White House had sharply criticized the seizure of Hamilton Hall, with a spokesman saying it was “absolutely the wrong approach.”

“That is not an example of peaceful protest,“ the spokesman added.

The protests, with Columbia at their epicenter, have posed a challenge to university administrators trying to balance free speech rights with complaints that the rallies have veered into anti-Semitism and hate.

The unrest has swept through US higher education institutions like wildfire, with many student protesters erecting tent encampments on campuses from coast to coast.

At Columbia, demonstrators have vowed to remain until their demands are met, including that the school divest all financial holdings linked to Israel.

The university has rejected the demand. Columbia has warned that students occupying the building face expulsion.