A fiery collision on Interstate 29 early this morning south of Sioux City at Sergeant Bluff killed one person and injured another. The one a-m accident involved two semi-trucks, one hauling a truck trailer, the other hauling food. Both northbound lanes of I-29 are closed. Woodbury County Sheriff Dave Amick confirms the death, and says the vehicle was engulfed in flames.Sergeant Bluff Fire Chief Bob Bartling says the exact cause of the wreck is still unclear.One report says the first truck driver hit the brakes when he realized he couldn’t clear the upcoming overpass and was hit from behind by the second truck. The injured driver reportedly has non-life-threatening injuries. No names have been released.