What Caused This Huge Semi-Fire?

From the looks of it, initially you're wondering if the driver was OK. But he was.

Thursday, Benton County Sheriff's deputies were on Highway 221 near Patterson when they came across this semi, fully engulfed in flames. Fire units were called and the blaze was extinguished, but no word on estimated damage to truck.

The driver, who managed to bailout safely, and sheriff's officials said it was likely a leaking fuel line caused the blaze.