Immigration and Customs Enforcement agents mistakenly detained a US citizen in a Chicago suburb Sunday morning, leaving him on the ground with various injuries, according to local authorities.

The man was found on the ground by police in Evanston, Illinois, after officers were dispatched around 9:49 a.m. over reports of two men arguing, Evanston Police Department said in a statement.

Several bystanders were helping the man, police said, and an ambulance was called after he reported injuries to his head, neck and teeth. Witnesses told officers they believed ICE agents were attempting to detain the man, who police identified only as an Evanston resident.

In cellphone video from a witness, a man can be heard saying “I’m a f**king US citizen.”

The incident marks the latest instance of a US citizen swept up in the Trump administration’s sweeping immigration crackdown, which has seen federal agents use highly visible, aggressive tactics that have sparked nationwide protests, legal battles, and political backlash.

One year after “Operation Midway Blitz” – the immigration crackdown by ICE officers in Chicago and surrounding areas – legal challenges against the agents’ aggressive tactics are still underway.

While responding to the scene in Evanston, one officer encountered two SUVs near an intersection and spoke with an individual in one of the vehicles, who identified himself as a federal agent conducting a “fugitive investigation,” police said. The person was wearing plain clothes and a vest marked “POLICE” with federal law enforcement markings, according to police.

The individual told the officer that agents had attempted to identify a person who resembled someone they were seeking, but the person refused to provide identification and “resisted detention,” Evanston police said.

The agents later determined the man was not the person they were seeking and learned that he was a US citizen, after which he was released, police said.

The Department of Homeland Security told CNN that ICE agents conducting a targeted enforcement operation encountered a person who resembled their target and “immediately identified themselves as law enforcement.”

“The individual was given lawful commands but was not cooperative and refused to identify himself,” a DHS spokesperson told CNN. “ICE officers relied on their training and later left the scene without further incident once the individual finally identified himself.”

Evanston police said it is investigating the incident, and that officers are preserving available body camera footage and interviewing witnesses.

Video shows struggle with agents

Surveillance video obtained by CNN appears to show two agents and the man in an upright struggle before federal officials pull him to the ground.

Moments later, at least three drivers pull into the nearby parking lot and exit their vehicles, joining other bystanders, some recording.

Cellphone video shot by a witness, which begins in the middle of the confrontation, shows the man being held on the ground.

Two agents are seen standing behind a black SUV, with one appearing to hold the man down, in the video obtained by CNN. A man’s voice is heard saying, “I’m a f**king US citizen.” The officers, one of whom was masked and wore a hood, then appear to release him and step away from the man.

The man, who police have only identified as an Evanston resident, can be heard telling the officers not to touch him as they move away from him.

Moments after releasing the man, the two agents return to their vehicles and leave the scene, while the man continues to lie face down on the ground in the street. A man wearing a cap kneels beside the man, gently touching his back and appearing to call for help, while several others are also heard trying to help.

Evanston’s police chief met with the man at a local hospital, and an evidence technician photographed and documented his injuries.

DHS said the man refused assistance from ICE agents, but did not address the man’s injuries in its statement.

Evanston police said its officer noticed blood on hands of the agent in the SUV, which the federal official said resulted from an injury he received while trying to detain the man. The agent declined medical treatment.

‘He was shooken up’

At the time of the incident, five federal agents were operating in separate vehicles to search the area for their target, the agent in the SUV told the Evanston officer.

Miguel Olivares told CNN affiliate WLS he was taking a break while helping out at a Mexican restaurant on Howard Street when he noticed vehicles parked outside and a confrontation unfolding.

“It looked like police vehicles until I started hearing, ‘I’m a US citizen. I’m a US citizen,’” Olivares said, at which point he began filming.

“They were being rough with him; they had him pinned against the floor, and it looked like one of the agents hit him in the face,” Olivares said.

He and others tried to comfort the man after agents released him.

“He was shooken up. He wasn’t really able to talk much. All he said was that he was a US citizen, that he doesn’t know why they targeted him,” Olivares told WLS.

The federal agents later left the area after protesters began to gather, fearing they would be attacked, according to local police.

“ICE has authority for lawful arrests where authorized under 8 USC 1357. Law enforcement officers use ‘reasonable suspicion’ to investigate immigration status and probable cause to make arrests consistent with the statute and the Fourth Amendment to the U.S. Constitution,” a DHS spokesperson said.