A federal law enforcement source told CBS News that local police arrested eight people. The official said some of those apprehended were wearing body armor.

Eleven people are facing charges over a “planned ambush” that led to an officer being shot outside an Immigration and Customs Enforcement detention facility in Alvarado, Texas, last week, federal officials announced Monday.

Alvarado police offers were dispatched to the detention center in the 1200 block of Sunflower Lane around 10:56 p.m. Friday, according to the Johnson County sheriff’s office. The call was made to investigate a report of “a suspicious person.”