After witnesses held a man down, stopping him from taking off from an intentional hit-and-run, the man died, the Fontana Police Department said Monday.
The struggle was caught on camera by a witness.
On Monday, a man was driving a stolen car and displaying "bizarre behavior" in a Kaiser Hospital parking lot at 9961 Sierra Avenue just before noon, according to police.
Local news from across Southern California
Police said the man, later identified as Ivan Reyess, 28, intentionally crashed into another car, then tried to run away.
He began fighting with several witnesses, later identified as Kaiser employees, who tried to stop him from running, arming himself with a large rock.
"He was throwing rocks, attempting to pull bushes out of the ground. Just acting bizarre," Doug Imhof, a Fontana police lieutenant, said.
The cellphone video shows the Kaiser employees holding Reyess face down to the ground as he thrashed beneath them.
Within minutes, Reyess stops thrashing. Fontana police arrived and began performing CPR on Reyess. Paramedics arrived and took him to the emergency room at Kaiser, where he was pronounced dead.
Police said they don't know what the cause of death is, but it is unlikely that the Kaiser employees who held him down will be arrested.
"If their actions were reasonable in taking this gentleman into custody, then that's just the way it goes. And that's the way it looks, at this point," Imjof said.
The man who shot the cellphone video who did not wish to be identified told NBC4 that moments before the video began, Reyess went after a man and his toddler. Police confirmed this account.