HEMPFIELD TWP., Pa. -- A Westmoreland County teenager died in a crash on Wednesday, just three weeks after her mother passed away.

Rachel Parker, 18, died in a crash along Route 119 in Salem Township.

Parker's mother died on June 4, Parker's graduation day from Greensburg-Salem High School. She had been battling cancer.

VIDEO: Victim Dropped Off Friends Moments Before Crash

Police said the 18-year-old's life was cut short when her vehicle, for an unknown reason, crossed the center line, crashing head-on into another vehicle. Parker had just dropped off some friends before going to work at the Sonic restaurant along Route 30 in Hempfield Township.

Parker was a cheerleader, and was on the homecoming court this year, friends said.

"She has a few close friends obviously that aren't here now today because of this. There are some other employees who have broken down. It hasn't completely set in yet," said Adam Cook, manager of Sonic.

The other driver suffered serious injuries and was being treated at a local hospital.

Police are still investigating the cause of the crash.