ST. LOUIS • The parents of a 12-year-old boy who was shot to death while home alone with his younger brother were charged Wednesday with involuntary manslaughter.

Damian Holmes, 12, and his brother, 9, were left home alone Tuesday night in the 3300 block of Michigan Avenue when they found a gun and started playing with it, police said.

A round struck Damian in the head about 10:35 p.m; police are not saying who fired the shot.

The boys’ father came home and took the 12-year-old to the hospital where he was pronounced dead.

Donnie L. Holmes, 41, was charged with second-degree involuntary manslaughter, two counts of endangering the welfare of a child, two counts of unlawful possession of a firearm and four counts of marijuana possession.

The probable cause statement said Holmes and his wife, Yolanda Jackson, had left the boys home alone. A handgun and shotgun both were in the house, along with ammunition for both. The handgun was not secured, and the boys got to it.

Lab tests of substances that officers found in the house showed the presence of drugs, including amphetamine, cocaine and marijuana.