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.

A local immigrant rights organization said more than 45 people were detained in the operations, which were described as “random sweeps.”

Federal immigration authorities carried out enforcement activities at several locations in Los Angeles on Friday, with some clashes breaking out as crowds gathered outside a warehouse and other locations across the city to protest the activity.