A big rig fell off a Southwest Freeway overpass in Sugar Land Thursday and landed on a car below. Amazingly, the woman in the car survived.

Police say the trucker was trying to avoid an accident when he jack-knifed, flipped off the overpass and landed on the frontage road at University.

“I thought I was walking up to someone who was seriously injured, if not dead," said Cory Mullarkey, a witness. "That’s what terrified me. I was almost hesitant to look up under there.”

The truck was carrying an empty load. Otherwise, the car he landed on would have been crushed, according to an officer at the scene.

“It’s truly God’s gift that she turned out all right," Mullarkey said. "If that truck was full of whatever, she could have been crushed.”

PHOTOS: Woman survives after big rig lands on her car

Mullarkey was one of the witnesses who helped the woman get out of the car.

"Well, she was very lucky that there were people who saw the accident, who rushed to her aid and helped her get out of the vehicle," said Doug Adolph with the Sugar Land Police Department.

She and the truck driver were taken to an area hospital with non-life threatening injuries.

Another nearby car was damaged by debris but no one inside was hurt.

Investigators blame the wreck on weather and an erratic driver who they say crashed, causing the 18-wheeler to jackknife.