David Huerta, the president of California’s powerful public sector union, was released from the hospital but remained in federal custody Saturday after suffering injuries when federal officials arrested him during a protest.

David Huerta was detained while documenting an immigration enforcement raid in downtown Los Angeles. Federal authorities said he was arrested on suspicion of interfering with federal officers.

After a day of contention and little information about the nature of an immigration enforcement operation in Los Angeles, the Department of Homeland Security has finally released details about the joint operation conducted Friday morning.