The fires broke out about 10:29AM along Interstate 29 Northbound between the 20/75 Interchange and the Floyd Monument.
Crews responded to 3 separate fires. One of the fire caused a significant amount of smoke and fire crews had concerns about visibility on the interstate, they were able to get the fire knocked down and the smoke had cleared before assistance from law enforcement to control traffic arrived.
Assistant Chief Brad Robinson says the fires likely started by a passing train with overheating bearings or other sparks.
Sioux City Fire Rescue is on the scene of multiple grass fires.
There are 3 grass fires between the Floyd Monument and the Train Bridge on Interstate 29