A protest in downtown Tucson against President Trump’s immigration policies escalated Thursday evening. Three officers sustained minor injuries in clashes with demonstrators; no one was taken to a hospital, said Tucson Police Sgt. Pete Dugan.

One officer was hit in the face and another in the back, Dugan said. He wasn’t sure how the third was injured.

Three men were arrested on suspicion of aggravated assault on a police officer, Dugan said. A woman was arrested on suspicion of obstructing, and of failing to identify herself, Dugan said. All four will be booked into Pima County jail, he said. Their names were not immediately released.

Dugan said the police office of professional standards will investigate, after protesters complained about officers’ actions.

Tucson Police Lt. Jennifer Turner said the protest began at 4:30 p.m., in front of the federal building on West Congress Street at Granada Avenue, and by 6 p.m., included about 80 people. At that point, an officer issued an emergency call for assistance, she said.

Dugan gave this account:

The protest was peaceful until many started to enter the roadway, disrupting traffic on Congress. An officer was struck from behind and when officers tried to take a suspect into custody, members of the crowd surrounded the officers, moving closer. Some protesters locked arms and got in front of a police vehicle. Police used pepper spray to disperse the crowd.

“Unfortunately for those trying to peacefully protest,” police had to step in when officers were assaulted and the investigation was obstructed, Dugan said.

Protesters, who said they were demonstrating against ICE raids that began last week, disputed police accounts of the protest.

A protest organizer, Stteffanny Cott, said police overreacted to a peaceful demonstration.

“This was provocation on the side of the police,” Cott said, saying a police SUV blocked the route protesters intended to use between the federal building and their Armory Park destination. She said marchers were going around the police vehicle, and that the officer was revving the engine and the SUV nudged a Brown Beret demonstrator, David Leon.