HOLYOKE, Mass. (AP) — Holyoke police are investigating after a 12-year-old boy was shot with a BB gun while riding a school bus.

Police say the boy was struck in middle of the forehead at about 6 p.m. Thursday as the bus was bringing students home.

The driver immediately turned around and headed back to Kelly Elementary School and called police. The boy was treated at the scene for a minor injury and did not require hospitalization.

His name was not made public.

Lt. James Albert says it appears the pellet passed through an open window and struck the boy.

Witnesses say they saw what appeared to be two teenagers armed with what looked like a rifle hiding in an alley.

There was no word on arrests.