OLATHE, Kan. -- Two people were killed when their Ford Mustang slammed into the back of a parked tractor-trailer early Monday morning.

Officers were called to West 149th Street and South Lone Elm Road around 12:45 a.m. They said they are investigating whether the driver, Castin E. Ellis, 21, didn't see the tractor-trailer on the dark roadway, or if alcohol or drugs were involved in the crash.

Ellis was killed in the wreck. Her passenger, who was also killed, was identified as Nikolas Musto, 20.

The driver of the tractor-trailer was not hurt.