A protest in downtown Tucson against President Trump’s immigration law enforcement 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,

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, the Arizona Daily Star reports.