Calif. cop's 4-year-old son needs leg amputation after mauling by police K-9
California police officer's K-9 partner mauls 4-year-old boy [KTLA-TV]

A police officer's 4-year-old son's leg was amputated at the ankle after the boy was attacked by a K-9 officer in his care, the Los Angeles Times reported on Thursday.

Officials with the Rialto Police Department announced that the attack happened on Sunday afternoon at Officer Michael Mastaler's home.

Police said Mastaler released the dog in his backyard after returning from a weekend training session and was upstairs inside the home at the time of the attack. The dog bit the boy's leg when he went into the yard to look for his mother, who was out shopping with his 18-month-old brother.

Nearby residents heard the boy screaming. One of them, Jeff Houlemard, told KTLA-TV that he broke down a wooden fence to get into the yard to help the boy, but that the dog refused to let go despite Houlemard kicking him.

"I jumped on top of the dog and ripped his mouth open," Houlemard said. "I just started choking the dog."

Mastaler arrived at the scene of the attack and put the dog back in its cage while Houlemard's wife comforted the boy as they waited for medical attention.

KTLA reported that eight inches of the boy's left leg were amputated. He is expected to walk again with the help of a prosthetic leg. The family has begun raising funds online for prosthetic equipment and other expenses.

Mastaler was not disciplined by his department. The dog is being held under quarantine while officials decide whether it should be allowed to continue working with the department.

"Police K-9s are highly trained and usually work under the direct supervision of a handler," Capt. Randy DeAnda told the Victorville Daily Press. "Here, there was obviously a timeframe where the dog was not supervised. It was not intentional; it was not an aggressive dog just wandering around."

Watch KTLA's report, as aired on Thursday, below.