A 17-year-old apparently killed his girlfriend and then himself Wednesday night following what neighbors described as an argument in a rural southern Lancaster County home.

Michael Ryan Hollow died inside the Nottingham trailer home; his girlfriend Mae Marie Davis, 17, of New Providence was pronounced dead Thursday morning at a hospital.

Both were shot in the head — Davis twice — and a .22-caliber rifle was found near Hollow's body, State police Cpl. Adam Kosheba said Thursday.

No one reported hearing the gunfire, probably because it was a smaller-caliber weapon, the trooper said. The shooting likely occurred between 9:50 p.m. and 10:40 p.m.

The motive remains unclear, investigators said.

Neighbor Penny Carr, 38, told the Lancaster New Era that Hollow and Davis had dated for about a year and talked about moving in together. But on Wednesday, she said, she also heard them argue at the home.

"I usually get a hug from him but last night I didn't," Carr told the paper. "He didn't seem like he was really violent."

Neighbors described Hollow as a high-school dropout who lived in the home with his parents and sister, none of whom was home at the time. The sister found the pair, Kosheba said.

Bottles inside the trailer suggested someone may have been drinking Wednesday night, and tests would be performed on the couple for evidence of drugs or alcohol, Kosheba said.