(Big Rig burns)...It happened at around 6:30 Wednesday evening

. The semi was headed west on Interstate 8, east of Araby Road. It was headed to Calexico. The driver says he ran over a mattress in the roadway and it caught in the trailer axles. The driver says he pulled over and found the mattress was on fire. The fire quickly spread to the trailers, and engulfed the entire rig by the time fire crews could make it through backed up traffic. The Interstate was blocked off to allow crews to extinguish the blaze. No injuries were reported.