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ST. LOUIS, MO (KTVI) – All lanes are now open on Interstate 64/Highway 40 westbound. Westbound lanes of the highway were closed for about six hours just past Jefferson in downtown St. Louis. A tandem tractor trailer caught fire on the right shoulder just before 6:00am.

Emergency crews have been on the scene and have contained the fire to the truck and one of the trailers, but hotspots continue.

The St. Louis Fire Department says hazardous materials in the trailer were not on fire. But, because of the potential danger involving these hazardous materials, special precautions had to be taken. The material in the trailer has to potential of causing an explosion.

Fire crews ripped the burned out trailer into smaller pieces to make sure all burning material was extinguished.

Besides being cautious with the hazardous materials in the second trailer, limited water and the frigid temperatures have also made fighting the fire challenging.

At first, traffic backed up for about five miles, going back to the merge in Illinois. Drivers were advised to take alternate routes, and many started doing that. By 7:15am, traffic on side streets and alternative highways was getting thick. Accidents on Interstate 270 slowed the flow of vehicles even more.

At 11:00am, many commuters were still stuck in traffic in Illinois.

All westbound traffic on the Poplar Street Bridge is being diverted to either Interstate 70 or Interstate 44/55 downtown. It will continue until the highway is opened.

Firefighters expect cleanup to take several hours.

The driver of the tractor trailer is reported to have suffered minor injuries. He was taken to an area hospital.