Police and private security throng every entrance but one. Steel barriers line the streets. Students pack up belongings in their cars and leave for home - classes are cancelled, and exam plans are up in the air.

Everywhere there is gloom, and uncertainty about what happens next at Columbia University.

Students told the BBC that the university’s decision to call in police to clear a Gaza protest late on Tuesday, leading to a raid on the occupied Hamilton Hall and hundreds of arrests, has left the college community shattered.

The university president, Nemat Shafik, said that it was with great regret that she ordered the police raid against students and others she said had infiltrated the protest. It would “take time to heal”, she added in a message in the operation’s aftermath.

For students of this prestigious school in Manhattan, New York, how long is unclear.