Driver killed, after his truck leaves the I-29 roadway near Salix, crashes into some trees and catches fire.

Authorities closed Interstate 29 in western Iowa after a truck veered off the freeway and caught fire.

The driver of the truck was found dead, but it's possible he had a medical condition that led to the Thursday morning crash.

The Woodbury County Sheriff's Office says the incident happened when the truck, which was hauling a trailer filled with hamburger, veered off I-29 near Salix, south of Sioux City.

The truck crossed a shallow ditch, came to rest in trees and caught fire.

Both southbound lanes of the freeway were closed while crews fought the fire. Traffic was routed into Salix. One lane was reopened several hours later.