The two freight trains were on a section of track in Chaffee, Mo., early Saturday when they collided. One of the trains struck a pillar for the Highway M overpass, causing the bridge to buckle, Scott County Sheriff Rick Walters said.
Five people in two vehicles on the bridge, and two people on the trains, were injured, KSDK-TV, St. Louis, said. All were listed in fair condition.
CNN said the National Transportation Safety Board is investigating the incident.