A wave of demonstrations has spread across U.S. campuses over the last two weeks, led by students who have pitched tents or occupied buildings in protest of the Israel-Hamas war.

It started April 18 when police moved to break up an encampment at Columbia University in New York City. Since then, it has spread to dozens of other campuses from Harvard to the University of California, Los Angeles.

Students are calling on their colleges to stop doing business with Israel or companies they say support the war in Gaza. Some also have asked for amnesty for student protesters who could face suspensions or other discipline.

University officials have negotiated deals with protesters at campuses including Northwestern University. Others have called the police to clear camps or campus buildings, as happened at UCLA.

At least 2,000 people have been arrested at campus protests nationwide in the last two weeks, according to a tally by The Associated Press.