The actions of an off-duty US police officer have been called into question after he fired his gun during a confrontation with a group of schoolchildren on Tuesday afternoon.

Luckily, nobody was hurt during the altercation, but two boys - a 13-year-old and a 15-year-old - were arrested and taken to a Californian juvenile detention facility.

"Ongoing issues" with teenagers walking across the police officer's property were to blame for the confrontation, according to Anaheim police.

The 13-year-old boy allegedly threatened to shoot the off-duty police officer during the altercation, which police claim prompted the off-duty officer's response.

But mobile phone videos shot by two witnesses appear to show the off-duty cop roughing the boy up after he leaped to the defence of a female friend.

In one video, the boy claims he was grabbed by the off-duty police officer after protesting at him swearing at a girl who walked across his yard.

"That's not what I said," the officer said.

Another teenager yells at the police officer, but it is inaudible on the recording.

"Shut the f--- up," the officer responds. "You weren't even there."

"Let me go," the boy can be heard repeatedly yelling after being grabbed by the police officer.

As more people approach the off-duty officer while he holds on to the boy, he reaches into his jeans and pulls out what appears to be a gun - from which a single gunshot can be heard being fired.

"I didn't do anything to hurt you. All I said was to respect the girl. You told her to 'get off my property you piece of (expletive),'" the 13-year-old can be heard saying in one of the videos.

The two teenagers were arrested when police arrived at the scene, according to the LA Times .

The 13-year-old was arrested on suspicion of battery and making criminal threats, and a 15-year-old was arrested on suspicion of assault and battery.

Police did not arrest the off-duty police officer.

"During that confrontation, a 13-year-old male is alleged to have made a threat to the off-duty officer that he was going to shoot him," Sergeant Daron Wyatt with the Anaheim Police Department told KABC .

But the 13-year-old boy's mother has struck back at the police officer's claims that he threatened to shoot him.

"In reality he was saying, 'I'm going to sue you. You keep hitting me. You're hurting me. I'm going to sue you,'" his mother - whose name has been withheld by US media - said.

She believes her son has done the right thing after watching the videos.

"I didn't see him being aggressive. I saw him remaining as calm as he possibly could. I saw him trying to reason with the adult," she said.

But despite being proud of her son for doing the right thing, it hasn't stopped her from being thankful he is safe.