MINNEAPOLIS - Dennis and Jamie Winegar were stuck in late rush-hour traffic when the Mississippi River bridge beneath them began to shake. Their nephew yelled, "It's an earthquake!"

"Then we realized the bridge was collapsing," Jamie Winegar said. "Boom, boom, boom, and we were just dropping, dropping, dropping, dropping."

Behind the wheel, Dennis Winegar fought to keep their Houston family's Chrysler 300M under control.

"I slammed on my brakes and saw something in front of me disappear and then my car pointed straight down and we fell." He estimated they dropped about 50 feet, landing on a smaller car below them.

Other drivers were getting out of their cars and trying to help people off the bridge.

"Angels is what I call them," Jamie Winegar said.

Nearby on the ruined span, a school bus filled with children returning from a day of swimming hung at a slight angle on the broken concrete. Ryan Watkins said the bus bounced a couple of times, then stopped with its front door wedged against a concrete traffic barrier. He and the other children jumped out the rear door.

Catherine Yankelevich was still inside her vehicle as it tumbled into the Mississippi River.

"Cars started flying and I was falling and saw the water," Yankelevich said.

She was able to climb out the driver's side window and swim to shore.

"It seemed like a movie," she said. "I never expected anything like this to happen here."

Jay Reeves was driving about 135 metres from the bridge when he saw its green metal superstructure move and then saw a cloud of rust-colored dust. He had just left work, where he is director of emergency medical services for the American Red Cross office in Minneapolis.

As he hurried toward the bridge, Reeves could hear children from the bus screaming. At the same time, he heard a loud groaning sound from the metal bridge. People were still in cars on the roadway and in harm's way.

"I whistled as loud as I could, and I said, 'If you can hear my voice and you can walk, get out now!'" he said.

He carried one bleeding woman from the school bus to an area away from the bridge where medical crews could help her, and he helped a man wearing a construction worker's vest. With a quick exam, he could tell the man had broken ribs, so Reeves bound them. Once rescue workers were on the scene in force, he head back to Red Cross headquarters to help organize a response.

"Honestly, the first thought I had was, 'this isn't happening,'" he said.