UPDATE
(Polk County) -- Union Pacific Railroad crews remain on the scene after two dozen rail cars left the tracks early yesterday (Friday) in northeast Polk County. Authorities say a bridge collapse is believed to have caused the derailment.
The Polk County Sheriff's Office says a small bridge north of NE 102nd Avenue gave way around 5:30 a.m., causing between 20 and 25 rail cars to go off the tracks.
There were no injuries. Roads that were closed in the area have reopened.
(Photo from WHO 13)