Several people died and many were injured in the rush-hour collapse of a major interstate bridge over the Mississippi River in the US state of Minnesota on Wednesday evening.
Sections of the Interstate 35W bridge broke loose at about 6.05 p.m., plunging into the river, on to its banks and another roadway. Crumpled vehicles, huge slabs of concrete and twisted steel littered the area.
More than 50 vehicles tumbled 20 meters into the river and onto debris as the bridge collapsed into a plume of dust, smoke and screams.
At least 60 people were hurt, with broken bones, head, neck and spinal injuries.
"People were pinned. People were partly crushed, talking to rescue workers... telling them to tell their families goodbye" before they died, Minneapolis Police Chief Tim Dolan said.
Four people were confirmed dead and authorities said the toll was certain to rise. Mr Dolan said several more bodies were recovered yesterday but he did not provide a new death toll.
"It is still a tremendously dangerous scene," he said.
"Obviously this is a catastrophe of historic proportions," said Minnesota Governor Tim Pawlenty.
Witnesses said a frightening rumble came from the bridge, followed by a thunderous roar, before the 160-metre-span came down. Survivors also told the Minneapolis Star Tribune the bridge began to buck up and down.
"I'm lucky to be alive," Marcelo Cruz, 26, said repeatedly. Mr Cruz had to steer his van into a concrete rail to keep his vehicle from diving off a broken end of the bridge, which stood about 20 metres above the Mississippi.
Eight kilometres of the Mississippi, the longest US river and a key transportation route, had to be closed on either side of the collapsed bridge, said a spokesman for the US Coast Guard in St Louis, Missouri.
A school bus carrying about 60 children had a narrow escape, remaining intact despite the destruction around it. All those on board were saved, although 10 had to be taken to hospital.
The cause of the collapse was not yet known but the US Department of Homeland Security in Washington said there was no indication of terrorism.
Crews had been working on the bridge, which was built in 1967, to repair the surface, signs and guard rails. The bridge had been inspected in 2005 and 2006 and the Minnesota Department of Transportation found no structural defects.