(CNN) — Two freight trains collided at an overpass near Chaffee, Missouri, early Saturday morning, injuring seven people, authorities said.
The overpass collapsed when one of the trains struck a pillar, Scott County Sheriff Rick Walters said.
A fire broke out on one of the train engines and was extinguished, Walters said.
There were no cars on the overpass when it collapsed, but two cars on the highway drove into the collapsed structure in the dark, said Trooper Clark Parrott, spokesman for the Missouri State Highway Patrol.
Five of the injured were in the cars, and two on the train. All but one of the injured were treated and released from the hospital.
The National Transportation Safety Board dispatched a team to investigate the collision and bridge collapse, the agency said.