The incident happened around 9:50 p.m. Friday. Investigators said the man was lying down in his tent and never saw the bear when suddenly it clawed his head through the tent. He suffered a severe cut that required two dozen stitches.
"He felt something and he reached up and he had blood on his hands. Other people in the campground said that they did see a bear immediately in the area," said Patrol Capt. Cindy Wood with the Department of Fish and Wildlife.
The man remains hospitalized as Fish and Wildlife continue to search for the aggressive animal which will be put down once found.
Authorities captured a photo of the bear believed to have been responsible for the attack. Witnesses said the bear was around 120 pounds. Investigators said the victim is a seasoned camper and had been at the campground for a couple of days.
Residents in the foothills said they routinely see bears in the area, and one was captured on video just last week. But now the rare attack has residents on edge.
"Usually they're a little afraid of humans so they don't want to make contact. But this is the first time I've heard of one being that aggressive," Altadena resident Rosemary Blanchard said.
Authorities said Millard Canyon will remain closed for several more days. The victim is expected to make a full recovery.