Both drivers killed, after tractor-trailer and dump truck collide on southbound I-635 in Dallas County.

Emergency responders are working to clear a crash that killed two people along the southbound lanes of Interstate 635 in Balch Springs Friday.

According to the Deputy Chief of the Balch Springs Police Department, one vehicle crossed over the center median between Elam Road and Quail Road before colliding with another vehicle in the southbound lanes at about 12:15 p.m.

The dump truck came to rest on its side on the grass and caught fire, sparking a grass fire that spread toward Elam Road.

Both the driver of the pickup truck and the driver of the dump truck were killed in the crash.

It is not yet clear which vehicle crossed over the center median into oncoming traffic. A witness told NBC 5 that they saw the driver of the dump truck cross over the median and enter the southbound lanes where it collided with the pickup truck.

The southbound lanes of I-635 have been closed and drivers are being diverted at Lake June Road. Drivers are urged to avoid the area.