GRINDSTONE (AP) _ A man who was arguing with his girlfriend fatally shot his 12-year-old son in an apparent accident after he told the boy to get his shotgun, police said.

Michael Alvin Muha, 39, was charged with homicide, aggravated assault and reckless endangerment in the Sunday death of his son, also named Michael Alvin Muha.

Muha's girlfriend, Tasha Miciotto, was also wounded during the argument at their home in Redstone Township, about 40 miles south of Pittsburgh. She was expected to be released from a Pittsburgh hospital on Monday, state police Trooper Joseph Christy said.

According to a criminal affidavit, Muha asked his son to get a shotgun from his car during the argument with his girlfriend. Muha loaded the gun with two rounds and had been waving the gun around before it discharged, striking his son in the chest, the affidavit said.

"It doesn't appear that the young man was in an altercation with his father, so he may have been a victim of the gun discharging and him not being the intended target," Christy said.

Miciotto told police she turned to run when the gun went off, but was shot in the eye. When she turned around, she saw the boy lying on the floor, already dead, according to the affidavit.

A neighbor, Wesley Joseph Silva, told police he heard the elder Muha yell that "he was going to shoot somebody because he wasn't going to have this problem anymore," according to the affidavit.

Silva told police he heard a gun go off, then someone scream, "He's dead!" Silva called 911 after hearing the gunshot.

Another neighbor, Valencia Barnes, said the family was close-knit. The younger Muha was a student at Brownsville Area Middle School, where counselors were made available Monday for students.

"Mikey was a good boy, well-mannered, had a lot of things going on in his life," Barnes said.

The elder Muha was being held at the Fayette County Jail. It was not known whether he had an attorney.