Federal immigration authorities arrested 44 people Friday across Los Angeles, prompting clashes outside at least one location as law enforcement threw flash bangs to try to disperse a crowd that had gathered to protest the detentions.

Helmeted police in riot gear turned out on Friday evening in a tense confrontation with protesters in downtown Los Angeles, after a day of federal immigration raids in which dozens of people across the city were reported to be taken into custody.

The FBI confirmed it’s participating in the HSI raids, not just in Los Angeles but nationwide, “as directed by the Attorney General.”