Video Appears to Show Chicago Cop Stomp on Man's Head

— -- A video appearing to show a Chicago police officer stomp on a man's head as another officer has him pinned on the ground has led to an investigation of the incident, according to the Chicago Police Department.

In the cellphone footage recorded by witness Terrance Hobson, an officer can be seen trying to apprehend the man by holding him to the ground as he appears to resist. The other officer on the scene then approaches the man and appears to kick him in the head.

Some witnesses said they thought the man was dead after the stomp seemed to knock him unconscious, ABC station WLS-TV in Chicago reported.

He "lost consciousness, he stopped moving for like 25 or 30 minutes," one witness, Lenell White, described to WLS. "It looked like he was passing away."

The man was later taken by ambulance to Mount Sinai Hospital for treatment, according to WLS, which spoke with the Chicago Fire Department.

A spokesperson for Sinai Health System, which operates Mount Sinai Hospital in Chicago, told ABC News the man has been released from the hospital. They hospital declined to provide further information, citing privacy laws.

Activist Jedidiah Brown hosted a protest outside the Chicago Police Department's headquarters this morning, according to WLS. During the protest, WLS said Brown called for an end to what he saw as a departmental pattern of excessive force against African Americans.

Nearly 75 percent of people shot by Chicago police between 2008 and 2015 were black, according to a report released this past April by the city's Police Accountability Task Force. The task force was created by Mayor Rahm Emanuel late last year after public outcry following the shooting death of Laquan McDonald in 2014.

The report detailed what it called the "alarming rate" of the department's "racist or biased policing."

The Chicago Police Department told ABC News in a statement that it, "holds its members to the highest possible professional standards with a priority on treating all Chicagoans with respect. Upon viewing the video, Superintendent Johnson immediately asked the Independent Police Review Authority to investigate the matter while the department gathers more information about the case.

"After careful consideration and reviewing the video footage, Superintendent Johnson decided to relieve one of the officers involved in the incident that occurred on the 3900 block of West Grenshaw of his police powers while IPRA investigates the case," the department said. "Since his appointment, the Superintendent has stated that accountability begins with him down to the last police officer and that he will tirelessly work to rebuild public trust in the Chicago Police Department."

A representative from the CPD's Office of News Affairs declined to provide further information about the incident. The Independent Police Review Authority (IRPA), which the police requested review the incident, did not immediately respond to ABC News' request for comment.