Columbia University students chained themselves to a gate to protest the detention of Mahmoud Khalil by ICE. They also demanded names of trustees who gave Khalil’s name to ICE.

Columbia University student Mahmoud Khalil is being held in an immigration detention facility in Louisiana more than a thousand miles away from where the 30-year-old was arrested in New York in early March. Here’s what to know about the Central Louisiana ICE Processing Center, where he’s being detained while he fights to stay in the U.S.