Investigation ongoing after semi

The incident caused a major backup on Interstate 35 during rush hour on Tuesday.

The incident caused a major backup on Interstate 35 during rush hour on Tuesday.

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The incident caused a major backup on Interstate 35 during rush hour on Tuesday.

An investigation is ongoing after a semi-truck caught fire in Oklahoma City.

The incident caused a major backup on Interstate 35 during rush hour on Tuesday. The driver is expected to be ok but firefighters had to put in extra effort.

"Sometimes it's hot brakes, sometimes it can be electrical, like car fires that we deal with sometimes. But with this one, I can't really say what caused that," said Lance Burnett, battalion chief with OKC Fire.

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When firefighters got to the scene, they saw the semi-truck on fire. The cab was completely engulfed and was a total loss.

"Soon after that, we realized it was going to be a much larger incident, we had some runoff from that fire that was going to the storm drains, so we called Storm Water Quality," Burnett said.

Fire hazmat crews helped out with containing the blaze. Adding to the chaos, the Oklahoma Highway Patrol said a wheel came off the truck too.

"A lot of plastics and things, and also some fuel involved," Burnett said.

There's still a question about what the truck was carrying.

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"We got initial reports of one thing it could be, and since then I've talked with our PIO, and we have concerns it might be something else," Burnett said.

Eventually, one lane of southbound I-35 opened up so traffic could get by. Five thousand gallons of water and 45 gallons of foam were used to get the blaze completely out.

"Right now it looks like it started in the tractor area of the semi-truck," Burnett said.

Firefighters said there were no other injuries. OHP is investigating to see if the fire was caused by the wheel coming off the truck.

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