An 18-wheeler caught fire on I-20 at Spur 408 early Thursday morning, officials with the Dallas Fire-Rescue Department told WFAA. 

The truck was carrying chocolate truffles, which "proved difficult to extinguish," spokesperson Jason Evans said via email.

The fire reignited multiple times and caused major delays on the roadway as crews tried to put it out. 

It was initially reported at about 5:50 a.m., Evans said, and took them about two hours to extinguish.

The driver of the truck told first responders that the cab of the truck suddenly ignited while he was driving, so he pulled over and got out.  

The flames then quickly engulfed the entire truck, Evans said. 

When asked why the truffles proved difficult for crews to put out, Evans said it was described to him like trying to put out a fire at a mulch pile. 

"You have to put out the flames on the surface, dig out what was exposed on the surface before what was burning underneath would reveal itself," he said.