Image copyright AFP Image caption It is unclear what consequences the nine-year-old will face

A 13-year-old girl in Mississippi has died after allegedly being shot by her nine-year-old brother over a video game, police say.

They said the boy grabbed a gun on Saturday afternoon after his sister would not give up the controller.

He allegedly shot her from behind, and the bullet entered her brain.

A local sheriff announced on Sunday that the teen had died of her injuries in a Memphis hospital. It was unclear how the boy obtained the gun.

It is also unclear what consequences the nine-year-old will face.

"He's just nine," Monroe County Sheriff Cecil Cantrell told the Clarion Ledger.

"I assume he's seen this on video games or TV. I don't know if he knew exactly what this would do. I can't answer that. I do know it's a tragedy."

The children's mother was in another room, feeding other children lunch at the time of the incident.

Police are still investigating the circumstances of the shooting, including how the weapon - a .25 calibre handgun - was accessed.

"This is all new ground for us, we've never dealt with a kid shooting a kid at age nine," Sheriff Cantrell told local press.