Follow CBSDFW.COM: Facebook | Twitter

PLANO (CBSDFW.COM) – High speed and actual racing contributed to the February 11 car crash that killed two Shepton High School students according to Plano Police Tuesday.

According to Officer David Tilley, this is still a working investigation.

Tilley said after investigators spoke with witnesses and other teens involved, it was determined they were racing.

There was a car full of boys in one car and the three girls, including Samantha Sacks and Lilly Davis who were killed, in the Porsche SUV.

Police said they were racing southbound on Mira Vista. The boys were in the left lane and the girls were in the right lane.

They approached a stop sign at Wayfarer. The boys stopped, the girls did not.

Police said the girls ran through the stop sign, struck the curb on the right side of the vehicle, causing them to cross over two lanes of traffic.

The car hit a tree in the median, then caught on fire.

The boys in the other vehicle saw what happened and were able to pull the rear passenger out of the burning car.

First responders found the third girl, Kendall Murray on the ground outside of the vehicle.  She survived, had surgery and is recovering.

All three of the girls were students at Shepton High School,  a campus for ninth and tenth graders.