Police officers in Chicago are under investigation after video of an officer body slamming a woman, who then goes into a seizure, surfaced from Sunday's Pride Parade.

Officers were called to a 'battery in progress' in the doorway of Big City Tap, a bar at 1010 West Belmont. In the video, the responding officers are seen trying to break up a fight between people in the doorway and the bar's security staff.

A female with a slight build is seen going in to the group's center and raises a fist and swings at the bar's security guards.

An unidentified officer swiftly grabs her and pushes her to the ground - where she appears to begin having seizure.

While the officers are trying to break up a fight in a bar doorway in Chicago, a woman (wearing white) slides into the frame to take a swipe at what is believed to be the bar's security

The officer grabs the young woman from behind, as she is trying to land punches on what appears to be a member of the bar's security staff

In a matter of seconds the officer yanks the woman, who quickly ends up sprawled on the ground

The woman is swiftly brought to the ground by a responding officer who is in the middle of the fight outside the bar

Once the woman hits the ground she appears to start having a siezure with one onlooker screaming 'Why did you slam her?'

The officers clear the chaotic scene to attend to the woman who is on the ground

In the chaos of the scene that transpired around 9.30pm, a woman is heard off camera screaming 'Why did you slam her? She's having a seizure!'

The officers, who by now appear to have got the gathered crowd relatively under control, asks everyone to step back as they attend to the woman who is convulsing on the ground.

While it is unclear what the official prognosis was, one of the woman's friends took to Facebook and posted in the early morning hours of Monday 'We at the hospital praying for her.'

How the police handled the fight is being reviewed by the Civilian Office of Police Accountability (COPA), a spokesman for the Chicago Police Department told CWB Chicago.

Both the officer (left) and the young woman (right) have not been officially identified as of yet

A friend of the woman has been updating people about the incident on her own Facebook page (pictured with the woman in the incident, at a hospital in the early morning hours of Monday)

'CPD takes all force complaints seriously,' department Chief Communications Officer Anthony Guglielmi said.

'The woman was involved in a physical fight with a group of individuals. When officers arrived, they attempted to break up the disturbance by subduing the woman to the ground.'

The woman was not believed to have been brought into police custody.