An 18-year-old Christiana woman died Sunday when she was ejected from a vehicle in Chester County, investigators said.

Kayla M. Steffy was a passenger in a pickup truck that veered off a road in West Fallowfield Township just after noon, according to state police at Avondale.

The Dodge Ram 1500 went into a ditch, then struck a fence before flipping over, police said. Steffy was tossed out of the vehicle. She wasn't wearing a seat belt, according to police.

Pamela Tatum, 47, of Parkesburg, was driving the truck south on Daleville Road when she lost control just south of Route 10, investigators said.

The truck crossed the opposing lane before veering onto the shoulder, police said.

An ambulance took Steffy to Jennersville Regional Hospital, where she was pronounced dead.

Tatum wasn't injured in the crash, police said. Neither were two other teenage passengers — Andrew Tatum of Parkesburg and a 17-year-old Cochranville girl.

Steffy was the only occupant not wearing a seat belt, according to police.

The driver was cited for leaving her lane.

E-mail: bhambright@lnpnews.com