A series of surprise U.S. Immigration and Customs Enforcement sweeps in downtown Los Angeles on Friday prompted fierce pushback from elected officials and protesters, who decried the enforcement actions as “cruel and unnecessary” and said they stoked fear in the immigrant community.

Tensions remained high in downtown into the evening. The Los Angeles Police Department declared an unlawful assembly and ordered about 200 protesters who remained gathered by the Los Angeles Federal Building to disperse around 7 p.m.

The use of so-called less-lethal munitions was authorized at 8 p.m. following reports of a small group of “violent individuals” throwing large pieces of concrete at officers, police said. A citywide tactical alert was issued shortly thereafter.