A mountain lion attacked a 63-year-old man camping northwest of Nevada City, the California Department of Fish and Game said Monday.
The attack happened around 1 a.m. Sunday and lasted about two minutes, according to a news release.
Fish and Game authorities did not release the victim's name but said he is from Marin County.
Authorities said the man decided to stop and sleep for the night while on the planned hiking trip, and laid a sleeping bag out on a tributary to the Yuba River.
The man told officials that during the attack, the mountain lion bit and clawed him through the sleeping bag.
The animal bit into the man's cap and his clothes.
"The lion immediately began a ferocious attack. It bit him into his head. It bit him on the hands," said Patrick Foy, of the Department of Fish and Game.
It then stopped, moved away and stared at the man for a short time before running off, Foy said.
The victim drove himself to a Grass Valley hospital. He has since been released and is recovering at home with staples in his skin.
Fish and Game officials went to the hospital and confirmed the man had suffered severe scratches and puncture wounds.
They took his sleeping bag and several pieces of clothing for a lab exam in Sacramento.
Based on forensic evidence, the Department of Fish and Game concluded that the mountain lion that attacked the man is female.
Mark Kenyon, the state's mountain lion biologist, estimated there are between 4,000 and 6,000 mountain lions in California.
Kenyon said attacks of this nature are rare.
He said he did not know know why the mountain lion chose to attack in this situation.
Fish and Game officials said they have sent a half-dozen searchers with dogs to track the animal.
Lion tracks were found at the scene of the attack.
The dogs did track a house cat suffering from injuries "consistent with a lion attack," said the release.
The agency said the search would continue indefinitely and that the animal would be killed to protect the public from possible future attacks.
"Prevailing thought about mountain lion behavior is that once it attacks a human, the likelihood that it may attack again is increased," Kenyon said.
Officials did not release the exact location of the attack.
California has had 15 confirmed mountain lion attacks since 1890, including this most recent one. Of 17 victims, 11 have survived.
Officials reminded people that if they encounter a mountain lion, they should make noise, and if they are attacked, they should fight back.
Kenyon said based on limited knowledge about mountain lion behavior, the old recommendation -- to play dead -- no longer applies.
Along the South Yuba River on Monday afternoon, sunbathers lay on rocks, and swimmers splashed in the cool water.
"I've heard what to do when a mountain lion's around and stuff, so I feel prepared and safe," said Evan McCormick, of San Jose.
Britney Beffort, who is visiting from Colorado, said she was torn when told that the cat would be destroyed.
"I mean, obviously, I don't want it to hurt any other people, but at the same time, it is a mountain lion. You can't expect it to be a safe animal," Beffort said.
The Department of Fish and Game will continue to search the area.