By Giles Hudson, CBS 11 News

RIO VISTA (CBSDFW.COM) – The Tarrant County Medical Examiner has ruled the death of a teenager in a Wednesday night car crash a homicide.

The accident happened around 10:30 Wednesday night on Johnson County road 1106 west of the city of Rio Vista.

The Texas Department of Public Safety says a 2002 Volkswagen Passat was traveling at an unsafe speed down the small rural road when it lost control.

The Passat slid, rolling sideways and going into a ditch. It hit two trees in the process and split in half, landing on opposite sides of the road.

The impact ejected all four people inside of the vehicle.  All were wearing seat belts.

One passenger, identified as 18-year-old Charlotte Tillison of Rio Vista was pronounced dead at the scene.

The driver and the two other passengers, also teenagers, were all taken to Texas Health Harris Methodist Hospital in Fort Worth.  One of the passengers is in critical condition.

The posted speed limit on the road is 40 miles per hour.

DPS Troopers say the roadway was dry at the time of the crash.

The crash remains under investigation.