An 18-year-old Hico woman who was five months pregnant was killed Tuesday evening after state troopers say she fell off the roof of a moving SUV.

Holly Lynn Travelstead died about an hour and a half after the 6 p.m. wreck on County Road 2435, seven miles northwest of Iredell in Bosque County.

Brittany Hope Allen, 18, of Hico was parked at a low-water crossing on the road in a 1997 Chevrolet

S-10 Blazer. Travelstead was sitting on the top of the SUV when Allen accelerated abruptly, throwing her off the vehicle and to the ground, where she struck her head on the concrete, a Texas Department of Public Safety spokeswoman said.

Travelstead was taken to Hamilton General Hospital, where she was pronounced dead.

The wreck is still under investigation, the spokeswoman said.