OMAHA, Neb. (AP) — A 16-year-old boy has been arrested after he shot and wounded his younger brother with a homemade weapon.

Emergency crews arrived around 5 p.m. Friday at an Omaha home to find a projectile had struck a 13-year-old boy. He was transported to Nebraska Medicine, where he underwent surgery and is expected to remain for observation until at least Tuesday.

The older brother was taken to the Douglas County Youth Center on counts of second-degree assault and use of a weapon to commit a felony.

The boys’ mother said a makeshift bullet that discharged from a homemade musket sliced through a plastic sled the young boy was using as a shield. She says the incident was accidental.

The 16-year-old has since been released from the youth facility.