A car crash on a northwest Houston tollway killed two people Sunday night.

Officers said they responded to an accident at the 5700 block of North Sam Houston Parkway West and Highway 249 at 8:30 p.m.

According to police reports, a speeding car on the feeder road hit a curb, landed on its side, and skidded into a concrete pillar supporting the tollway overpass.  Officers said the impact crushed the roof of the vehicle, killing both of the car's passengers.

The victims -- a male and a female -- were in their late teens or early 20s.

Police said they are working to identify the victims and are trying to determine whether alcohol or drugs factored into the crash.