Police say a high school student in Billings, Montana was accidentally shot and killed on Sunday by a friend who was startled awake by pebbles the victim had thrown at his bedroom window.

“It’s a tragedy,” Capt. John Bedford told the Billings Gazette. “We have to investigate at this point for what it is, but it’s a tragedy all around.”

According to Bedford, the victim was 15-year-old Mackeon Schulte, a sophomore at Billings Senior High School. From KHQ:

The statement says Schulte and another boy showed up at their friend’s house around 2:30 a.m. Sunday. They knocked on his window and threw pebbles to wake him.

Police say the unnamed boy was startled and did not recognize the faces outside. He fired a gun that was in his bedroom, striking the victim in the head.

KTVQ reports that the 17-year-old shooter was questioned by police but later released. Authorities say investigators are meeting with county prosecutors to decide whether to file charges.

[Image via KPAX]