The Evanston Police Department began sending a supervisor to any reported immigration enforcement scene to document what happens and collect evidence for the Illinois attorney general's Civil Rights Division.

Police in a Chicago suburb are gathering videos and other evidence to forward to the Illinois attorney general's office following a car crash involving a U.S. Border Patrol vehicle that resulted in an arrest captured on video showing an agent repeatedly striking a man in the head while he was pinned to the ground.

Immigration agents detained three individuals after a sedan crashed into the back of the U.S. Border Patrol vehicle around noon Friday in the city of Evanston. The incident attracted a crowd of bystanders and rapidly intensified.

Videos shared on social media revealed some in the crowd seemingly attempting to interfere with the detentions. Federal agents are seen at times deploying pepper spray, punching a man who approached the officers, and pointing a gun in the direction of another woman who had opened the agents' vehicle door, where a detainee had been placed.

Federal agents have been spreading throughout Evanston in recent days, as part of President Donald Trump's immigration enforcement activities in the Chicago region. In response, some Evanston community members have set up "rapid response" teams, organizing to warn residents when federal agents are spotted and working to slow the agents as they travel through the region.

One agent appeared to kneel on a man's back Friday, punching him in the head as it was pressed against the asphalt. The Department of Homeland Security later said the officer delivered "defensive strikes" after the man being arrested "grabbed the agent's genitals and squeezed."

In a news conference shortly after the episode, Mayor Daniel Bis alleged immigration agents had "beaten people up" and "abducted them."

"It is an outrage," Bis said. "Our message for ICE is simple: Get the hell out of Evanston."

The Department of Homeland Security statement said the agents were being "aggressively tailgated" and the sedan hit them as they tried to make a U-turn.

"A hostile crowd then surrounded agents and their vehicle, verbally abusing and spitting on them," the agency said. "One physically assaulted a Border Patrol agent and kicked an agent. As he was being arrested, he grabbed the agent's genitals and squeezed them. The agent delivered several defensive strikes to free himself."

The mayor has urged more people to join the rapid response team, and city officials have passed ordinances declaring city property to be "No ICE Zones." This week, the Evanston Police Department began sending a supervisor to any reported immigration enforcement scene to document what happens and collect evidence for the Illinois attorney general's Civil Rights Division, said Police Commander Ryan Glew.

Glew said officers received calls from both federal agents and bystanders. A supervisor arrived after the arrests were made, and several people were treated by paramedics for exposure to pepper spray.

"When we responded those efforts were focused on stabilizing the situation and preventing further conflict between ICE agents and community members," he said.

Allie Harned, a social worker at Chute Middle School, was part of the crowd that formed after the collision.

"This was awful. There were ICE agents and CBP agents pointing guns at community members, spraying pepper spray in the face of community members," she said at the news conference. She later continued, "This was terrifying to community members, it was horrifying to a student who happened to be in a car and witnessed it. It is not OK."