DULUTH, Minn. (AP) - A semi driver suffered significant burns in an explosion inside his rig in Duluth.

Assistant Fire Chief Erik Simonson says waste oil was being transferred when a pump inside the semi backfired, igniting the collection of vapors Tuesday afternoon. Reports say the semi is from Rainy Lake Oil in International Falls.

Simonson says the driver suffered substantial second-degree burns to his upper torso. He was taken to a local hospital. His condition was not released.