WEST MIFFLIN, Pa. (AP) — Police in Pennsylvania say a 6-year-old boy has been shot to death by his 10-year-old brother while the two were home alone.

Allegheny County say officers and paramedics arrived at the mobile home in West Mifflin, near Pittsburgh, at about 9:45 a.m. Wednesday to find the 6-year-old with a gunshot wound to the head. He was taken to a hospital, where he died from the injury.

Investigators determined the boy's 10-year-old brother fired the gun in the mother's bedroom.

Superintendent Coleman McDonough says the boys' mother was at work when the shooting happened. He says the 10-year-old first called his mom and then called 911 at her urging.

The investigation is ongoing, and McDonough says there's "no excuse for a weapon to get in the hands of a child."