Jamie Winegar was one of dozens trapped in bumper-to-bumper traffic during rush hour on the Interstate 35W bridge in Minneapolis at 6 pm (0000 BST) when she started hearing a strange noise.

“Boom, boom, boom and we were just dropping, dropping, dropping, dropping,” she reported.

The car she was riding in landed on top of a smaller car but did not fall into the water.

She said her nephew yelled, “’It’s an earthquake!’ and then we realised the bridge was collapsing.”

Survivors told the Minneapolis Star Tribune that the bridge had begun to buck up and down before it crumbled.

“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 65ft (20 metres) above the Mississippi.

Not far off, a burning truck and a yellow school bus clung to one slanted slab of carriageway that drooped down towards the water. The bus, returning from summer camp with 60 children on board, had just crossed the bridge before it crumpled into pieces and was feet from the edge.

Christine Swift’s 10-year-old daughter, Kaleigh, was on the bus and called her mother.

“She was screaming, ’The bridge collapsed!”’ Swift said.

She said that a police officer told her all the children got off the bus safely, although ten were treated in hospital afterwards.

Peter Siddons, who was also caught in the traffic jam, said that he heard “crunching.”

“I saw this rolling of the bridge,” he said. “It kept collapsing, down, down, down until it got to me.”

Times Recommends

• 'Radio Rancid' is scourge of Obama
• French gulp as global warming alters wines
• Colton, the barefoot boy bandit, outfoxes sheriffs