A 13-year-old boy is being treated at a Montana hospital after suffering a gunshot wound over the weekend.

Gillette police officers responded to the 100 Block of Ross Avenue at 7:12 p.m. Saturday for a report of a gunshot wound, according to Lt. Brent Wasson. Officers arrived to find the boy with a wound in the upper part of one of his arms, near the shoulder area.

The bullet had traveled into the boy's chest, Wasson told K2 Radio News on Monday. The boy was taken to a local emergency room before being transferred to a hospital in Billings, where he was receiving treatment as of Monday.

Police determined that the weapon involved was a 9mm Ruger handgun belonging to the boy's 24-year-old brother. The older brother had been holding the gun when it discharged, Wasson said.

The case remains under investigation. As such, Wasson declined to release further details.