An 11-year-old Arizona boy fatally shot his grandmother and then himself after repeatedly refusing to clean his room, sheriff officials said.

The unidentified boy, who lived with his grandparents in Litchfield Park, was “being stubborn about” not cleaning his room on Saturday despite being asked several times by Doyle Hebert and Yvonne Woodard to do so, Maricopa County Sheriff’s Office Sgt. Joaquin Enriquez said in a news release obtained by The Post.

The boy then approached the couple from behind as they were watching television and shot Woodard, 65, in the back of the head, killing her with a handgun that belonged to Hebert, Enriquez said.

Hebert initially ran after his grandson but doubled back seconds later to check on his wife. He then heard a second gunshot and saw his grandson take a few steps before collapsing. Doyle grabbed the handgun and called police, Enriquez said.

Police were still investigating the murder-suicide, but so far found no evidence that the boy showed any previous signs of violent intentions.

“There was no cause for concern prior to this event,” Enriquez said.

Neighbors, meanwhile, were shaken up over the shooting, prompting some of them to hold a vigil outside the home.

“It’s just hard,” neighbor Danny Dillon told AZFamily.com. “You can’t get your mind around it, you just can’t.”

Dillon said the elderly couple and the boy had always been friendly to him and were courteous to neighbors.

“You have that neighborly connection but your heart just wishes that you had more and you could’ve done more,” Dillon told the website. “You could’ve seen something or said something.”