Police say a robbery suspect was killed Tuesday afternoon as he fled from police and was struck by an 18-wheeler while crossing Interstate 35 in North Austin.

The fatal crash shut down part of the highway on Tuesday, leading to major delays in the area near the U.S. 183 interchange.

Austin police responded at 1:45 p.m. to the Shell gas station on I-35 and St. Johns Avenue for a report of a robbery by assault. When officers arrived, a woman believed to be involved in the robbery drove away in a tan vehicle while a man took off running, police said.

Officers pursued the man through a nearby parking lot before he ran onto Interstate 35 near U.S. 183 and was struck by an 18-wheeler, police said. He was taken by Austin-Travis County EMS medics to Dell Seton Medical Center in downtown Austin, where he later died, officials said.

The driver of the 18-wheeler did not stop and is being sought by investigators, police said. They also are still looking for the female robbery suspect, who police described as in her 40s. Anyone with information can call the police’s vehicular homicide unit at 512-974-6935.

Northbound I-35 was closed from U.S. 290 to Rundberg Lane on Tuesday afternoon as authorities investigated the incident. Traffic was diverted to the frontage road, and the Texas Department of Transportation briefly waived tolls for Texas 45 and Texas 130 northbound. Capital Metro bus routes in the area were also delayed.

Drivers were urged to avoid the area and to expect heavy delays and closures during the investigation.