(WIBW/KCTV) - Authorities were still looking Wednesday night for a semi truck and driver involved in an accident with a pregnant woman's car.

The wreck happened Wednesday morning on I-35 in Johnson County. The Kansas Highway Patrol says 33-year-old Nikki McClure was trapped in her car after she hit the back of tractor trailer authorities say was moving much slower than regular traffic. McClure's car then went off the road.

KHP says her seatbelt likely saved her and her baby's lives. McClure gave birth to a healthy baby girl after the accident, about a month earlier than expected.

Investigators believe the semi driver did not know the accident occurred, but they want to talk to him. They say the vehicle should have damage to its rear.

Authorities ask any witnesses to contact the Highway Patrol.