The man's father, a former Orange County sheriff's deputy, claims police used excessive force while arresting his son. The Fullerton Police Department is investigating the incident.
There were several people present when the incident happened at about 8:30 p.m. Tuesday near the Fullerton Bus Depot. At least two people who did not want to appear on camera said they were yelling at police officers to stop.
Police say the fight ended when the suspect lost consciousness.
Kelly Thomas, 37, is on life support at UCI Medical Center. His parents and brother are hoping for a miracle, but are grief-stricken by the reality.
"There's definite brain damage at this point already," said Thomas's father, Ron Thomas. "It's horrific. I've never -- in my Army career, in my law enforcement career -- I have never seen a person look so bad."
The former Orange County sheriff's deputy admits his son was homeless and had a history of mental illness. But he accuses the Fullerton Police Department of using excessive force Tuesday night when they confronted his son near the bus depot in Fullerton.
"They've killed my son. They've killed him. No weapons," said Ron Thomas.
Police say they received a call reporting someone breaking into cars. Officers allege they talked with Kelly Thomas at the scene, but when they tried to arrest him Thomas fought back for several minutes. Thomas stands 5 feet 10 inches tall and weighs 165 pounds.
"There were probably at least six officers there trying to subdue Mr. Thomas, having great difficulty in subduing him while they were trying to take him into custody," said Fullteron Police Sergeant Andrew Goodrich.
Police say the fight continued until Thomas lost consciousness. He was then hospitalized. His father says his son's face is almost unrecognizable.
"He was slammed extremely hard, however it happened, and that's the only injuries on him to cause him near death," said Ron Thomas.
His father says hospital reports show his son did not have drugs in his system. Police say Kelly Thomas was not armed. They will not say if they Tasered him since the incident is under investigation, and so far the department cannot comment on whether excessive force was used.
"We're going to conduct a thorough investigation and if there were any actions that weren't justified, then that will come out in that investigation," said Goodrich.
Police said two officers suffered broken bones during the fight and were treated at a hospital.
Court records also show that Kelly Thomas did plead guilty to assault with a deadly weapon more than 16 years ago. Ron Thomas said Kelly is not a violent man. Police say that they have no record of Kelly Thomas being this violent in the past.
Thomas's family must decide whether to remove him from life support.