Emergency crews have resumed their recovery and clean up efforts at the scene of the Interstate 35W bridge that collapsed during rush hour Wednesday evening.
Authorities lowered the number of confirmed fatalities to four, but said they expect the number to change throughout the day.
Doctors at Hennepin County Medical Center said at a news conference this morning that 79 people were injured in the disaster.
One of them died around midnight of blunt force trauma, consistent with chest injuries from falling 64 feet.
Fifty-five people were transported to area hospitals including 24 to HCMC. Six of those had life-threatening injuries, 10 were listed in satisfactory condition and eight were treated and released.
Twenty-four people made it to hospitals on their own.
Dr. John Hick, who was one of the first responders to the bridge collapse, said "It's somewhat of a miracle that (the number of injuries and fatalities) was that low."
Hick also praised work done by passersby and people in area who jumped in to assist police and paramedics with evacuating injured.
Dr. William Heegaard, who operated on some of the injured, said the hospital cleared out 25 rooms in ICU to deal with the expected flood of injuries.
He said at one point the hospital had 10 operating rooms available and that a number of surgeries were performed. "They were in shock, they were happy to be alive, but they felt sad for all the people they had seen," he said.
Doctors said the types of injuries dealt with included head, arm, leg internal injuries
"They may make it, but some of the may not, said Dr. Douglas Brunette.
Police Chief Tim Dolan said at a news conference this morning that 20 to 30 people were still missing.
Dolan said many vehicles were still in the water.
"The recovery involving those vehicles and the people who may be in those vehicles is going to take a long time," Dolan said. "We're dealing with the Mississippi River. We're dealing with currents, and we're going to have to do it slowly and safely."
Police Lt. Amelia Huffman said the number of confirmed fatalities had been lowered from seven to four. "This morning, the medical examiner's office only has four sets of remains," she said.
Mayor R.T. Rybak said the police department's number is based on the medical examiner's information, but he still considers there to be seven fatalities and he expects more.
"I think you can expect that to be a dynamic situation for a while," he said.
Crews in boats were using sonar to search the water, said Hennepin County Sheriff Rick Stanek. The bridge is too unstable to allow divers into the water, he said.
As the sun rose this morning at least two patrol boats were visible on the river south and east of the lock and dam and just uptream from the collapsed bridge.
Many rescuers who'd been at scene as late as 2 a.m. were expected back at 6 a.m. for an operations briefing. Then, they were going to go back onto the water.
An hour before sunrise, nearly a dozen giant lights mounted on the Cedar Avenue and surviving parts of I-35W bridge illuminated river surface.
The 1,907-foot bridge fell into the Mississippi River and onto roadways below. The span was packed with rush hour traffic, and dozens of vehicles fell with the bridge leaving scores of dazed commuters scrambling for their lives.
Stanek told the Associated Press at about 1 a.m. today that all search efforts had been called off for the night and that searchers did not expect to find any survivors.
Wednesday night, Gov. Tim Pawlenty said the bridge collapse "is a catastrophe of historic proportions for Minnesota."
Between 50 and 60 vehicles were on the bridge when it went down shortly after 6 p.m., authorities said. Legions of rescue workers and volunteers swarmed to the scene and spent hours sifting through the wreckage in a frantic search for survivors.
By late in the evening, officials said efforts at the Mississippi had switched from rescue to recovery.
Jay Danz, 45, of St. Paul, was on his way to the Metrodome to watch the Twins play Kansas City and had driven under W. River Parkway, beneath the interstate bridge, seconds before it fell.
"I heard it creaking and making all sorts of noises it shouldn't make," Danz said. "And then the bridge just started to fall apart."
In addition to the cars that went into the water, a school bus carrying about 60 Minneapolis children fell from the bridge, landing on all four of its tires and missing the water as it came to rest near the parkway.
Several of the children and at least two adults were treated for injuries after the group escaped through the back door of the bus.
"Some kids had blood on their faces, but thank God everybody could move," Danz said.
Bernie Toivonen of Minneapolis was southbound on I-35 Wednesday when he saw the bridge in front of him buckle.
"I knew it was going down," he said.
Toivonen scrambled out of his vehicle, and helped others who were stranded among the wreckage.
"I helped a lady get out of a minivan. She was at a real steep angle. There were people screaming."
Toivonen said that below him 40-50 feet was a tabletop of concrete. He scrambled down to the scene and found a man who he said, "had a chunk of a beam on his arm and a piece of concrete on his head."
The cause of the collapse wasn't known in the hours afterward. It's too soon to know what happened, said Catherine E. Wolfgram French, a civil engineering professor at the University of Minnesota.
"Things can happen with temperature, and with construction, or a lot of other confounding factors," French said.
This was a 40-year-old truss bridge, and French did say that some early truss bridges don't have as many structural redundancies -- backups to carry the loads -- as is now considered desirable.
Another engineer, Michael Ramerth, a principal at MBJ Consulting Structural Engineers in Minneapolis, said in the search for answers "I would start at the foundations."
On a typical weekday, more than 100,000 cars use the bridge.
Berndt Toivonen, 51, of Minneapolis, was on his way home from a painting job when the bridge collapsed beneath his car.
"The bridge started to buckle," Toivonen said. "It went up and came down. I thought I was going to die."
What people in the area of the collapse experienced or saw at about 6:05 p.m. unfolded as motorists crawled bumper to bumper across I-35W toward the end of rush hour.
Those on the bridge felt buckling and swaying and heard a crunching.
Then came the unthinkable: The 40-year-old bridge collapsed, dumping vehicles into the water and onto land below. That was followed by scenes of frantic, bloodied motorists and rescuers who converged on the scene.
Many vehicles, including at least one semitrailer, were on fire. People were reported to be floundering in the river. Rescuers rushed to help people escape cars trapped in the V-shaped hollow where the bridge had caved in.
The school bus that fell was, returning from a day-camp swimming trip sponsored by a Waite House summer program.
"We collapsed," said Ryan Watkins, one of the children.
Crumpled wreckage lay on the east bank of the river, and a huge section of concrete roadway lay on the west bank. Down below in the river gorge, rescue workers scrambled to help people get out of the water.
Fire and black smoke rose from the wreckage.
Memorial Blood Centers and the American Red Cross put out immediate calls for blood donors. A center for families of those who are missing was set up at the Holiday Inn Metrodome.
Homeland Security Secretary Michael Chertoff issued a statement Wednesday night saying there was no indication of terrorism.
Transportation Secretary Mary Peters was scheduled to fly to the Twin Cities early this morning, along with Sens. Norm Coleman and Amy Klobuchar.
Workers on the bridge
About 20 construction workers employed by Progressive Contractors Inc. were about to begin night shift work on the bridge when it collapsed, company officials said.
The company has been working on a repair project for about six weeks, said Mike McGray, president of the company. Progressive is based in St. Michael, Minn., and is one of the state's major road and bridge repair contractors.
In 1990 a construction worker fell 90 feet to his death when a concrete arch span on the Lake Street-Marshall Avenue Bridge collapsed into the Mississippi River. In 1960 a bridge over the Minnesota River at Hwy. 41 in Chaska collapsed during construction. No one was killed in that incident.
Construction workers had been repairing the bridge's surface as part of improvements along that stretch of the interstate. There were a large number of construction workers who went into the water, said Maj. Michael Asleson of the Minnesota State Patrol.
Most of the injured were taken to Hennepin County Medical Center.
Nine people were taken to North Memorial Medical Center in Robbinsdale and five others arrived by ambulance at the University of Minnesota Medical Center.
A staging area for the injured was set up near the Stone Arch Bridge.
Marcelo Cruz, 26, of Crystal, who has used a wheelchair since being paralyzed in a shooting in South Carolina several years ago, was driving his van across the bridge toward downtown when he felt it began to wave up and down.
He steered into the concrete railing to stop himself from driving into the river, and saw many cars on the bridge fall into the water.
His van came to rest steeply inclined toward the river and several onlookers ran and told him to get out. He said he needed help and the onlookers carried him out of his van in his wheelchair to safety on the riverbank.
"I'm lucky to be alive," he said over and over again.
Peter Siddons, a senior vice president at Wells Fargo Home Mortgage, was heading north over the bridge toward his home to White Bear Lake when he heard "crunching."I saw this rolling of the bridge," he said. "It kept collapsing, down, down, down until it got to me."
Siddons' car dropped with the bridge, and its nose rolled into the car in front of him and stopped.
He got out of his car, jumped over the crevice between the highway lanes and crawled up the steeply tilted section of bridge to land, where he jumped to the ground.
"I thought I was dead," he said. "Honestly, I honestly did. I thought it was over."
Ramon Houge of St. Paul was on his way home from work and was on the bridge when he heard a rumbling noise and cars in front of him began to go down.
He said cars that could backed up, turned around and drove toward safety.
Baseball game added to congestion
Danz said there were cars behind him on W. River Parkway, but he didn't think any of them were under the bridge when it fell.
John Joachim of Taylors Falls, Minn., took I-35W to the Twins game and said traffic suddenly "slammed to a stop" as he neared University Avenue.
"I didn't know what was going on but a huge cloud of dust rose in front of us," he said.
After the game, traffic were being rerouted away from the collapse, routes that also were being used by theater patrons leaving the Guthrie.
This afternoon's Twins game has been postponed, along with scheduled groundbreaking ceremonies for the new baseball park that had been scheduled for this evening.
'Five feet from the edge'
Louis Rogers, 28, of Roseville was driving home from work listening to music in his Chevy Blazer when the bridge gave way just feet in front of him.
"It just disappeared; it made no sound whatsoever," he said. "It was pretty much like a thud, not too loud of a thud. The next thing I know, cars were dropping and there was smoke. My car was no more than five feet from the edge."
Rogers tried to help some of the people in cars that had fallen into the river and stopped on the bridge.
"I saw a lady in a car and I screamed, but I got no response," he said. "I grabbed my bag and started signaling cars to get out of there."
Ryan Murphey, 30, of Minneapolis, went to the scene to see if he could help out.
"It looked like a terrorist attack, a complete catastrophe," Murphey said. "But everyone there was very calm and organized."
He helped remove two victims from the east side of the bridge on stretchers, including a woman in her late 50s with a "bloody face."
The Twins decided to play Wednesday night's game, but only after the public address announcer alerted the crowd at 7:08 p.m. of the bridge's collapse. A moment of prayer followed. It was then announced that the game would go on so emergency crews could perform their duties without the added pressure of having 20,000 to 25,000 people scrambling in swarms from the Dome area.
Area law enforcement, including the Hennepin County Sheriff's Office, had launched at least three boats to help with the rescues.
"Unbelievable," said Audrey Glassman of Minneapolis, who left her work shift at nearby Spoonriver restaurant to survey the scene. "You'll never cross a bridge again without thinking about this."
Red Cross volunteer Eric Pone guessed 100 people came through the Holiday Inn Metrodome Wednesday searching for word on loved ones. "For some folks they're dealing with a sense of relief because they're loved ones are OK. Others haven't heard anything."
Ian Anderson rode his bike to the Holiday Inn to look for his girlfriend, Allysa Rocklitz, 24, of Burnsville, a waitress at the Fine Line club in downtown Minneapolis. "I can't remember a single instance when I called her and wasn't able to instantly talk to her," he said. "She calls me all the time and all of a sudden she's not there.
"Hopefully, I'll get a call tonight. I'll be up all night, I'm sure of that."
--The Associated Press contributed.