An 18-wheeler hauling dozens of cows overturned on a highway bridge just east of Jackson, killing 40 animals and blocking traffic for hours.

The Tuesday night accident occurred on the so-called "Stack," stalling traffic on the U.S. 49 flyover bridge until about 4 a.m. Wednesday.

Pearl Fire Chief Rob Martin says the truck, which was hauling 120-130 head of cattle, ended up on the edge of the guard rail. He said the trailer portion was heavily damaged.

Martin says a firefighter at the scene was injured and treated at a hospital before being released. No other injuries were reported.