Emergency personnel respond to the scene of a train derailment near Rockview, Mo., on Saturday, May 25, 2013. The National Transportation Safety Board has launched an investigation into the cause of a cargo train collision that partially collapsed a highway overpass in southeast Missouri, injuring seven people. (AP Photo/The Southeast Missourian, Fred Lynch)

Photo by: Fred Lynch

Emergency personnel respond to the scene of a train derailment near Rockview, Mo., on Saturday, May 25, 2013. The National Transportation Safety Board has launched an investigation into the cause of a cargo train collision that partially collapsed a highway overpass in southeast Missouri, injuring seven people. (AP Photo/The Southeast Missourian, Fred Lynch)