A mountain lion attacked a pygmy goat in a Portola Valley backyard last week and then scampered off when a woman rushed out of her house screaming and waving her flashlight at it, authorities reported.

The mountain lion attacked the goat last week in the backyard of a home at 797 Wayside Road, near a popular hiking area, according to a written statement from San Mateo County Sheriff's Lt. Ray Lunny.

The homeowner told sheriff's officials that she heard a commotion around 9:30 p.m. and went outside to see one of her pygmy goats lying on its side in her fenced-off backyard while a 100-pound mountain lion paced nearby.

The woman said she screamed and waved her flashlight at the mountain lion, which then jumped over the fence and ran into the foliage.

A veterinarian that came to the house found two puncture wounds on the goat's neck, consistent with a mountain lion attack, Lunny said. It wasn't clear whether the goat died, and Lunny did not return phone calls seeking comment.

The woman called the sheriff's office and a deputy found two mountain lion paw prints near where the cat fled. It was Portola Valley's second reported mountain lion sighting in three days. A lion had been spotted Feb. 17 in the 3000 block of Portola Road.

The sheriff's office sent an e-mail to Portola Valley residents via the county's SMC Alert system, telling them to keep a close watch on small children and avoid jogging or hiking at dawn, dusk or at night, when the animals are most active.

Sheriff's officials said the area around the site of the goat attack has an abundance of deer — the primary prey for mountain lions. But it's not uncommon for the cats to attack livestock and house pets, said Kyle Orr, a spokesman for the California Department of Fish and Game.

A Santa Cruz family has lost two pygmy goats to mountain lions since December, but Orr said state officials have not seen a significant uptick in attacks recently.

"They're opportunistic predators," Orr said. "If they're hungry and there's a goat and they're able to access it, they're going to take it."

A state fish and game warden told the homeowners they could obtain a depredation permit, which allows residents who have lost livestock to kill the mountain lion if it returns. The homeowners declined, saying they didn't want the cat harmed, Orr said.

Mountain lion attacks on humans are extremely rare, with only 14 documented cases in California since 1890, Orr said.