Dan Richmond had walked about two miles on the Mount Wilson trail in the Angeles National Forest when he was confronted by a large bear.
"All of a sudden, I saw this bear standing on its hind legs and I'd never seen a bear in person before, so I was pretty freaked out," he told CNN affiliate KTLA.
The standing bear was taller than him, said Richmond, who is 5"11.
"I turn around and there's another bear coming out towards me. At that point, I was trapped. I yelled at the top of my lungs to attempt to scare it away."
The noise initially seemed to work as one of the bears retreated about five or six feet.
"And I thought, 'Maybe this is my chance to run right past him,'" Richmond said.
'I just stayed really, really still'
That's when one of the bears attacked him.
"It's hard to imagine until one attacks you and you just feel the strength of its jaws and its body," 54-year-old Richmond told KTLA from his hospital bed.
"He first grabbed my wrist," Richmond said.
"He actually put his mouth around my neck. And I just stayed really, really still."
"Once I knew that he was attacking me, I did not fight back. I just stayed silent. I was down on my hands and knees, and I was perfectly still because it was the only chance that I had."
The bear was on top of him, but after a while, "he kinda eased up," Richmond said.
"I got up and I walked away," he said.
"Once I thought it was clear, I just started running down the mountain."
He ran back to his home in Sierra Madre and called for help.
'I'm just really fortunate'
Richmond suffered multiple lacerations, with injuries in the back of his head, neck, legs and upper torso, said Sierra Madre Police Chief Larry Giannone in a news conference. He also suffered a partial head injury after falling backwards when the bear attacked him.
"He sustained what we'd know as a pretty good bear attack," Giannone said.
He noted that bear attacks in the area were very rare. The pair could've been mother and cub, the police chief said.
"We have bears in the area looking for food and water," he said. "They're typically non-aggressive. We've had officers that typically walk right by them and they shoo them back into the foothills."
The city of Sierra Madre posted on Facebook that there was no immediate threat to the community. Two trails have been shut in the meantime.
The US Forest Service and the California Department of Fish and Wildlife will investigate. The state authorities will determine what will happen if the bears are found.
In the meantime, a stunned Richmond counted his blessings.
"I'm just really fortunate," he said.