The mountain lion was discovered early Saturday morning.
Amalee Spray, 23, was asleep in her home in Sage, east of Temecula, when she was awakened by the sound of her three Chihuahuas barking.
Spray went outside and found that the dogs had the mountain lion backed into a corner of her garage.
She called police, who were stunned when they arrived to find the full-grown mountain lion being held at bay by three tiny dogs.
About 45 minutes later, a game warden arrived. He tried shooting the mountain lion with rubber bullets to scare it off, but according to a spokesman for Fish and Game, the animal advanced on the warden, who then fired his shotgun, killing it.