CHAFFEE, Missouri (AP) - A highway overpass in Missouri collapsed early Saturday when rail cars slammed into one of the bridge's pillars after a cargo train collision, authorities said. Seven people were injured, though none seriously.
The bridge collapsed after a Union Pacific train hit the side of a Burlington Northern Santa Fe train at a rail intersection.
Derailed rail cars then hit columns supporting the highway, causing it to buckle and partially collapse.
The National Transportation Safety Board launched an investigation into the cause of the cargo train collision, which happened about 2.30 am near Chaffee, a town of about 3,000 people.
The crash came more than a week after a commuter train derailment outside in Connecticut that injured 70 people a disrupted service for day. That accident involved a railroad used by tens of thousands of commuters north of New York City.
In northwestern Washington state this past week, a bridge collapsed when a truck driver's load bumped against the steel framework.
NTSB board member Robert Sumwalt said while the investigations into both collapses are in the early stages, "there is no similarity" between the Missouri accident and the bridge collapse in Washington, which sent two vehicles and three people falling into the chilly water.
He noted that the Missouri bridge was rated "good" after it was last inspected in February.
"This was not because of any lack of integrity of the bridge in southeast Missouri, but because of a train that derailed and had a bunch of rail cars slamming around, which knocked down a pier, which allowed the bridge to collapse," he said.
"If you just look at the facts, there is no relationship other than some external object caused each of these bridges" to collapse, he added.
The overpass that collapsed in Missouri was about 15 years old and in good condition but just couldn't withstand the impact from the rail cars, Scott County Sheriff Rick Walter said.
Only two vehicles were on the overpass at the time of Saturday's collision. Five people in the vehicles were taken to a hospital, along with a train conductor and an engineer. All seven had been released by Saturday afternoon, hospital spokeswoman Felecia Blanton said.
"You're driving down the road and the next thing you know the bridge is not there. ... It could have been really bad," Walter said.
The crash derailed about two dozen rail cars hauling scrap metal, automobiles and auto parts, tossing them into the overpass' support columns. The highway was shut down for about 13 kilometres.
Two 12-metre sections of the overpass buckled while the two cars were on the roadway, sending the cars into the edges of the collapsed sections. A diesel fire also broke out in one of the locomotives after the collision, but was quickly extinguished, Mr Walter said.