LOS ANGELES (AFP) - An 11-year-old boy in Arizona reportedly shot his grandmother in the back of the head and then turned the gun on himself, apparently because he was upset at being asked to clean his room.

Yvonne Woodard, 65, was shot on Saturday (Nov 3) in her home in the town of Litchfield Park, north-west of Phoenix, as she watched television with her husband.

The couple had full custody of the child and the grandfather told police that he had been asked to clean his room all day but had refused.

Maricopa County Sheriff's Office spokesman Joaquin Enriquez told local media that the couple were sitting on their couch watching TV when the boy came up behind his grandmother and shot her.

The grandfather ran after the boy but then went back to help his wife, at which time the boy shot himself.

Police said the gun belonged to the grandfather.