Glendale police are investigating an arrest that happened at Dick's Sporting Goods inside the Glendale Galleria over the weekend.
Cell phone video begins showing Glendale officers in uniform and plain clothes punching and kicking someone while they're on the ground.
In the video, police can be heard saying, "Turn around!" while the man can be heard saying, "I can't breathe!"
It's unclear what happened before the video begins.
Glendale police say they are aware of the video that has now gone viral -- and the department has opened up an internal investigation.
Four of the officers in the video have been placed on paid administrative leave.
The person they took into custody was wanted for stealing at a different store in the mall, but did not say which, police said.
The person was eventually arrested on charges of larceny and resisting arrest, officials said.
"Glendale police officers are held to a high standard and we work hard to maintain the trust of our community," the department said in a statement. "We take these types of incidents very seriously. Appropriate actions will be taken following the investigation."