A prominent Palestinian activist who helped lead Columbia University’s 2024 student encampment protests was arrested Saturday night in New York City by federal immigration authorities who claimed they were acting on a State Department order to revoke his green card, according to his attorney.

Mahmoud Khalil was at his university-owned apartment blocks from Columbia’s Manhattan campus when several Immigration and Customs Enforcement agents entered the building and took him into custody, Amy Greer, his attorney, told The Associated Press.

One of the agents told Greer by phone that they were executing a State Department order to revoke Khalil’s student visa. Informed by the attorney that Khalil, who graduated in December, was in the U.S. as a permanent resident with a green card, the agent said they were revoking that too, according to Greer.

In a statement to CBS News, the Department of Homeland Security said Khalil’s arrest was “in support of President Trump’s executive orders prohibiting anti-Semitism,” alleging the former student “led activities aligned to Hamas.” The department did not provide details of any charges or alleged crimes.