The Dallas County Sheriff's Office says three other people were hurt in the accident Tuesday morning.
Investigators believe the crashes happened after one car hit a barrier and then collided with another car, sending the second vehicle into an 18-wheeler. Two people in the first vehicle were killed. Several other vehicles then piled into the accident scene.
Authorities are trying to determine what caused the accidents and whether racing was involved. Names of the victims were not immediately released.
Traffic was diverted during cleanup of the accident scene.