Officials confirmed Thursday that the 40-year-old bridge that collapsed in Minneapolis on Wednesday had been rated "structurally deficient" but was considered safe for use.

A boat takes part in the search on Thursday for victims of Wednesday's bridge collapse in Minneapolis.
(Jim Gehrz/Minneapolis Star Tribune/Associated Press)

"There was a view that the bridge was ultimately and eventually going to need to be replaced," Minnesota Gov. Tim Pawlenty said during a news conference.

"There was no call by anyone that we're aware of that said it should be immediately closed or immediately replaced. It was more a monitor, inspect and maintain, and replace it in the future."

The eight-lane bridge collapsed under rush-hour traffic at 6:05 p.m. CT Wednesday, sending more than 50 cars plunging 20 metres into the Mississippi River. Four people were killed and dozens more injured, and with many cars submerged in the Mississippi River, the death toll is expected to rise.

In 1990, the U.S. government gave the bridge a rating of "structurally deficient," citing significant corrosion in its bearings. A 2005 federal inspection also rated the bridge structurally deficient.

During the 1990s, inspections found fatigue cracks and corrosion in the steel around the bridge's joints, and repairs were made.

Dan Dorgan, of the Minnesota Department of Transportation, said there were cracks in the welds since the day the bridge was built, but those cracks were stable. Inspections in 2005 in 2006 found no evidence of additional cracking or growth of pre-existing cracks.

'This is not a rescue operation anymore; it's a recovery mission.'— Minneapolis fire Chief Jim Clack

"For those reasons, we felt the bridge was fit for service," said Dorgan, explaining that the entire bridge would have had to have been jacked up to allow the bearings to be repaired.

Dorgan said that 77,000 bridges in the U.S. — about 13 per cent of all bridges in the country — are structurally deficient.

Tom Everett, of the national bridge inventory program, later said that designating a bridge structurally deficient does not indicate the bridge is dangerous or must be replaced.

Families search for information about the missing

About 20 families gathered at an information centre late Wednesday in search of information about loved ones they couldn't locate. Rescue workers say as many as 30 people are unaccounted for.

Ron Engebretsen and daughter Jessica talk to reporters Thursday about wife and mother Sherry, who died in the Minneapolis bridge collapse.
(Jerry Holt/Star Tribune/Associated Press)

Two young women and their father said earlier Thursday that they were praying for the safe return of mother Sherry Engebretsen, who was driving home from work when the bridge collapsed.

"I know she's living right now, I just know it," said daughter Jessica Engebretsen, 18. "She's really strong. I just know she is. That's all we have to believe right now."

But Thursday evening, Sherry Engebretsen was confirmed as among the dead. She was from Shoreview, just north of Minneapolis.

The other people confirmed dead were all from the Minneapolis area:

• Julia Blackhawk, 32
• Patrick Holmes, 36
• Artemio Trinidad-Mena, 29

Minneapolis fire Chief Jim Clack said it was unlikely more survivors would be found.

"This is not a rescue operation anymore; it's a recovery mission," Clack said Thursday. 

Body recovery could take 3 days

Recovering bodies trapped in the rubble could take as long as three days as divers search in submerged cars, twisted steel, slabs of concrete and the strong currents of the Mississippi River, emergency officials warned Thursday.

"This is going to take a long time," Minneapolis police Chief Tim Dolan told reporters. "We're going to be careful and use the experts."

Police on Thursday lowered the confirmed death toll from seven to four. Hospital officials counted 79 more injured.

Dolan warned the number of fatalities could rise.

"We are estimating anywhere from 20 to 30 people could be out there," he said.

The divers were taking down licence plate numbers of vehicles so authorities could track down their drivers, Hennepin County Sheriff Richard Stanek said.

The eight-lane Interstate 35 W bridge, a major Minneapolis artery, was being repaired, and two lanes in each direction were closed when the bridge buckled and broke into several massive sections that fell into the Mississippi River below.

Between 100,000 and 200,000 cars a day crossed the bridge, according to officials.

U.S. President George W. Bush said the federal government will help ensure the bridge is rebuilt as quickly as possible.

"We in the federal government must respond, and respond robustly, to help the people there not only recover, but to make sure that lifeline of activity — that bridge — gets rebuilt as quickly as possible," Bush told reporters in Washington Thursday.

'Boom, boom, boom and we were just dropping'

As authorities at the site shifted their efforts to recovering bodies, tales of horror and heroism emerged from survivors of the wreckage.

Jamie Winegar of Houston described sitting in traffic when she started hearing "boom, boom, boom and we were just dropping, dropping, dropping, dropping."

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 realized the bridge was collapsing."

A school bus that dangled precariously on the edge of one of the broken concrete slabs was carrying about 60 children, but all inside the bus escaped.

Jeremy Hernandez was one of the adults in the bus. 

"You could hear kids moaning and crying," he said. "When the dust settled down, they all just started screaming, screaming, 'We're going to go in the river, we're going to go in the river.'

"My heart started beating fast and I just jumped over the seats and I opened the back of the door … and tried to throw kids off the bus."

Others reported seeing bystanders dive into the water to try to help people trapped in submerged vehicles.

With files from the Associated Press