Gun shop records led police to arrest a man who, they say, shot a pregnant woman as she rode a motorcycle on I-79 earlier this month.

Martin C. Patterson, 47, of Ambridge, is charged with aggravated assault and reckless endangerment in the Aug. 2 shooting of Alisa Musser. Mr. Musser, 26, was riding as a passenger on the southbound ramp toward Neville Island when she felt what she thought was a rock from a passing car hit her left side.

Hospital workers later removed a .223-caliber bullet from her side. Police went to the Coraopolis Sportsman's Club after the incident, where they found boxes of .223-caliber Wolf rounds in a garbage can, according to an affidavit. The boxes had price tags from Sportsman's Warehouse on Mt. Nebo Pointe, where records showed Mr. Patterson was one of three people to recently purchase them.

When police interviewed Mr. Patterson at his house, he admitted shooting at the Coraopolis gun range on Aug. 2 along with a friend, the affidavit said.

"I'm sorry for shooting the girl, and it was an accident," Mr. Patterson later told police, according to the affidavit.