MINNEAPOLIS, Minnesota : A freeway bridge collapsed over the Mississippi river Wednesday, killing at least six people and leaving drivers stranded on massive chunks of concrete amid the rushing water.
Several cars were flung into the river and a semi truck caught fire after it was sliced in half.
Several other cars were crushed as parts of the bridge were sheared off.
In Washington officials said there was no sign that the bridge's collapse was the result of terrorism.
"We have confirmed six deaths and we are continuing the search," Mayor R.T. Rybak said at a press conference.
"At this point, we have searched approximately 50 cars...we have confirmed that this will be a very tragic night when it is over."
Images shot by local television crews showed a disastrous scene of people crouching on bent and crumpled concrete with parts of the bridge submerged in the brown river as smoke and flames rose complicated rescue efforts.
A school bus full of children was on the bridge but did not fall into the river as it collapsed, local media reports.
Several of the children were injured.
The bridge was under construction at the time of the accident and only one lane was open in either direction.
Russ Knocke, spokesperson for the Department of Homeland Security, told AFP that there was no suggestion of terrorism involved in the disaster.
"There are no indications of a nexus to terrorism at this time," Knocke said.
"We continue to monitor the situation. State and local officials have the lead in rescue and response efforts."
At least eight cars and a truck went into the water, the Minneapolis Star Tribune reported.
Rescue workers scrambled into the river gorge to help people off the huge chunks of concrete roadway as fire and smoke rose from the wreckage, the paper said.
The 40-year-old arch bridge which rises 64 feet (20 metres) over the river was undergoing repairs at the time of the accident, and there were reports that construction workers were using a jackhammer at the time of the collapse, AFP has learned.
Ramon Houge was driving on the bridge when he heard a rumbling noise, saw the ground collapse in front of him and watched cars go down into the water.
Traffic was bumper-to-bumper at the time, and he estimated hundreds of people must have been involved.
"It didn't seem like it was real," he told the Star-Tribune.
Those still on solid ground backed up as best they could and he saw kids on a yellow school bus with blood on their faces.
Sarah Fahnhorst, who lives in an apartment a block away from the bridge, heard a huge thud and then "the entire building shook. It shook the ground," she told the paper. - AFP/ch