Hundreds of people gather in Foley Square, New York, to demand the release of Mahmoud Khalil, a leader of pro-Palestinian demonstrations at Columbia University who was arrested by US immigration officials over the weekend despite holding a permanent residency green card. "Mr. Khalil's detention has nothing to do with security. It is only about repression," says Baher Azmy, one of the lawyers representing the recent Columbia University graduate and a prominent face of the university's high-profile protests. [COMPLETES VIDI36ZZ79Q_EN] IMAGES AND SOUNDBITES