Hundreds of protesters flooded the lobby of Trump Tower Thursday to denounce the arrest of Mahmoud Khalil, a Palestinian activist detained by ICE over his involvement with pro-Palestinan demonstrations at Columbia University.

Police, staged inside and outside the Fifth Avenue building before the demonstration, warned protesters to leave or face arrest.

Police have begun arresting demonstrators from a Jewish group who filled the lobby of Trump Tower to denounce the immigration arrest of Mahmoud Khalil, a pro-Palestinian activist who helped lead protests against Israel at Columbia University.

The Trump administration has undertaken a radical attempt to deport Mahmoud Khalil, a permanent U.S. resident and Palestinian activist. Immigration agents took him into custody on Saturday at Columbia University, where he had helped organize and negotiate on behalf of the group Columbia University Apartheid Divest.

Palestinian activist and former Columbia University grad student Mahmoud Khalil, who played a significant role in the Gaza protests at Columbia last year, was arrested by federal immigration authorities.

Mahmoud Khalil is a green card holder who played a role in pro-Palestinian protests at Columbia University and is now facing deportation by the Trump Administration. NBC News' Tom Llamas spoke to one of his attorneys,