MOUNT PLEASANT, Pa. (CBS NEWS)-- A 14-year-old boy was charged Monday with killing a 13-year-old boy after shooting him in the face while they were playing with a gun at a Pennsylvania home, police said.

The 14-year-old, of Mount Pleasant, was arraigned after being charged as an adult with criminal homicide and illegal possession of a firearm by a minor.

The shooting Sunday night didn't appear to be intentional, but police were continuing to investigate and trying to determine who owned the weapon, said Jerry Lucia, Mount Pleasant's mayor and fire chief.

The dead boy, James Gustafson, is the son of a borough firefighter and had planned to become a junior firefighter when he turned 14 in June, Lucia said at a news conference.

"Every time he'd come by the station, which was every day, he'd express to us that he couldn't wait until June," he said.

The 14-year-old told police the boys were playing with the gun when Gustafson was shot. Several other people were in the home at the time, but authorities didn't specify who they were. In Pennsylvania, criminal homicide is an umbrella charge filed when police contend one person killed another.

The incident happened at a friend's house, so there are three families involved in the tragedy, the mayor said.

"When something like this happens, especially in a small town, (you ask) 'Why did it happen? It shouldn't have happened. What can we do to prevent these things?" Lucia said.

Both boys were students at Mount Pleasant Junior/Senior High School, where grief counselors and other support services were being offered Monday.

"We stand together to support the family and friends as well as one another through this difficult time," school Superintendent Timothy Gabauer said in a statement.

Online court records don't list an attorney who could speak on behalf of the suspect, who faces a preliminary hearing March 31.

Mount Pleasant is about 40 miles southeast of Pittsburgh.