NEW ORLEANS — A truck stop cashier spotted a sex offender and a Florida teenager who’d been missing for a week, setting off a 40-mile chase across Louisiana swampland that ended when a tire on the man’s stolen truck burst into flames, officials said Thursday.

The man got out of the truck – taken from the Florida Panhandle – with a knife, and officers subdued him with a stun gun and a police dog, said Cpl. Paul Mouton of the Lafayette Police Department. Officers then got the girl out of the truck.

Steven Myers, 41, of Plant City, Florida, and the girl both were in serious but stable condition from knife wounds, officials said. Investigators believe but have not confirmed that Myers stabbed the girl and then himself, Mouton said.

“To hear that your daughter, your baby, has been stabbed … I wouldn’t wish that on anyone,” the girl’s father said at a news conference in Tampa, near their home in Valrico. The Associated Press is not identifying the girl or her family because of allegations she was sexually assaulted.

The teenager had been missing since June 11. She is bipolar and didn’t take her medications with her when she last left home, officials said. Her family and neighbors had passed out fliers along the interstate and started social media campaigns to find her. The girl wasn’t kidnapped, but Myers manipulated her, Hillsborough sheriff’s Col. Donna Lusczynski said.

Lusczynski and Sheriff Brett Stassi of Iberville Parish, where the chase began, both said Myers stabbed himself after getting out of the truck, and told police to shoot him.

Myers will face charges of attempted murder, unlawful sexual activity, and others, officials in both states said. He had served two Georgia prison sentences, the first for a 1999 conviction on child molestation charges and the second for a parole violation. He was released in February 2012 and later registered as a sex offender in Plant City.