The U.S. Department of Homeland Security is defending its policy of having Immigration and Customs Enforcement officers arrest people at their immigration court hearings after a group of immigrants and advocates filed a class-action lawsuit that seeks to stop the practice.

Federal immigration officers have detained 2,792 undocumented immigrants in the Los Angeles area since June, according to the U.S. Department of Homeland Security. Officials didn’t specify in which counties or cities the arrests occurred.

Civil rights groups sued the Trump administration on Wednesday in a bid to stop the government’s policy of allowing Immigration and Customs Enforcement officers to arrest undocumented migrants who show up for immigration hearings at courthouses.