A California woman punched a mountain lion and tried to pry open its jaws to stop it from attacking her small pooch — but the helpless pet died from his injuries, according to new reports.

The Simi Valley woman had opened the door to let her 10-year-old miniature schnauzer, Pumbaa, outside around 2 a.m. Thursday when she spotted the puma in her backyard.

The small dog charged at the big cat — which attacked, the owner’s brother, who only identified himself as Brian D, told KTLA.

So the petrified owner jumped into action.

“She jumped on top of the mountain lion and she tried to pry the mountain lion’s jaws open to save her dog,” he told the outlet. “She loved this dog like a child.”

“She got a cut on her finger, and she kept trying to stop the mountain lion from killing the dog for all she could,” he added to ABC 7. “She said she was punching it and kneeing it in the head and trying to pry its jaws open, and it just wouldn’t let go. The whole time she could hear her baby dying.”

The frantic owner said the animal didn’t even realize she was there until after her dog died, according to the report.

The mountain lion growled at her, prompting her to run back inside.

She called police while the wild animal was still in her yard.

Responding authorities had hoped to scare it away using a less-than-lethal beanbag shot — but it got away even before that, Simi Valley police Sgt. Keith Eisenhour told KTLA.

The same cougar is believed to have attacked another dog, a Havanese named Sammy, about four hours earlier.

Sammy’s owner, Michael Cheng, told the station he was taking the 8-year-old pup for a walk when the cat attacked.

He threw a jacket over the animal’s head and pummeled it to get it to drop his pet — which it did.

But that didn’t stop the mountain lion from later returning to his home and trying to enter through a doggie door.

“I certainly hope that the Animal Control could somehow set a trap to capture the mountain lion, because it’s putting everyone in danger here,” Cheng told the station.

Local residents are especially alarmed because authorities have no idea where the mountain lion is, KTLA reported. It was believed to have been radio-collared, but the GPS is no longer transmitting.

Though there is no definitive proof, the big cat could be P-35, a nearly 10-year-old female known to inhabit the Santa Susana Mountains, Ana Beatriz Cholo, a spokeswoman for the Santa Monica Mountains National Recreation Area, told KTLA.

P-35 was being studied in that region before her collar stopped working.