CHICAGO (AP) — Authorities arrested 21 protesters Friday outside a Chicago-area federal immigration facility that activists say functions as a de facto detention center and is plagued by inhumane conditions. The Cook County Sheriff’s Office reported that the arrests occurred by midday while they verified identities and potential charges. Just moments before the clash, demonstrators filled the area with singing and chanting. Around 10 a.m., a large group, aware of the arrests that were imminent, crossed the protest barrier in an attempt to walk closer to the U.S. Immigration and Customs Enforcement facility.

Some protesters carried signs that read “God’s Love Knows No Borders” and “God Demands Freedom,” while others engaged in prayer. The crowd swelled to about 300 before dispersing. Law enforcement included officers from the Illinois State Police and Cook County sheriffs’ police.

The facility in Broadview, Illinois, has seen regular protests, especially on Fridays, against a federal immigration initiative dubbed “Operation Midway Blitz,” which has resulted in over 3,200 arrests in the Chicago metropolitan area of individuals suspected of violating immigration laws since September.

The aggressive tactics used by agents from Customs and Border Protection and U.S. Immigration and Customs Enforcement have faced growing criticism through legal challenges and public protests.