BELLEVILLE, Ind. – A Pennsylvania teenager suspected of killing his girlfriend’s parents in an argument over her curfew was captured in Indiana yesterday with the girl in his car after a police chase that ended in a crash. The 14-year-old girl was not hurt, authorities said.

David Ludwig, 18, and Kara Beth Borden were taken into custody around midday after he crashed his parents’ car head-on into a tree in Belleville, some 600 miles from where the killings took place. Police were questioning Mr. Ludwig but had not spoken with Kara. Because of her age, Indiana and Pennsylvania law requires a relative, guardian or attorney to be present.

Investigators said it was not immediately clear whether the girl was abducted or went along willingly, but they were operating on the assumption she was kidnapped.

“It’s completely insane, completely insane,” Lancaster County, Pa., Coroner G. Gary Kirchner said. “This isn’t a Romeo-and-Juliet deal. This is far worse than that.”

Authorities said Ludwig shot Kara’s parents, Michael F. and Cathryn Lee Borden, early Sunday after they and their daughter argued about her curfew when she came home late. The shootings happened at the family’s home near Lititz, Pa., about 60 miles west of Philadelphia.

An alert for the girl was issued across the East, and police in Pennsylvania and Indiana investigated reported sightings of the pair as they made their way west in a red Volkswagen Jetta. They were stopped in Belleville, about 20 miles west of Indianapolis.

Mr. Ludwig led police on a five-mile chase at speeds of 90 to 95 mph.

Trooper David Cox said Mr. Ludwig was “very reckless, very dangerous at that point,” meeting vehicles head-on and running them into a ditch before he hit the tree. After officers pulled Mr. Ludwig from the car, Borden got out and was frantic, screaming and crying, Trooper Cox said. No weapons were found in the car.

Kara’s 13-year-old sister, Katelyn, told investigators her parents were shot after they argued with Mr. Ludwig for about an hour, according to court papers.

Katelyn said she saw Mr. Ludwig shoot her father, and then ran into the bathroom, where she heard a second shot, presumably the one that killed her mother, court papers said. Mr. Ludwig then ran through the house calling for Kara, she told investigators.

Stephanie Mannon, 16, said Mr. Ludwig and Kara had been seeing each other secretly. “Their parents didn’t approve of them being together” because of the age difference, she said. “It wasn’t because he was a shady character, because he wasn’t.”

Both Mr. Ludwig and Kara maintain Web sites. Hers refers to interests in soccer, art, and her Christian faith; his says he enjoys “having soft air gun wars” and claims expertise in “getting in trouble.”

The Bordens, both 50, were apparently shot once each in the head, authorities said. Mike Borden worked for a printing company, and the children were home-schooled, said neighbor Tod Sherman.

Mr. Sherman said the family knew Mr. Ludwig through a home-schooling network.