Tricia McLaughlin, a spokeswoman for the Department of Homeland Security, said in a statement that federal agents were trying to arrest a man from Venezuela who was in the country illegally in a “targeted traffic stop” at around 6:50 p.m. She said that he fled from agents.

When the officer caught up to him, Ms. McLaughlin said he “began to resist and violently assault the officer.” She said two people came out of a nearby building and, along with the man being sought, attacked the officer with a snow shovel and a broom handle.