(CBS/AP) An elite team of Navy divers joined the search Tuesday for victims of the collapse of a Minnesota bridge that killed at least five people, bringing greater experience and more sophisticated technology to the search for bodies in the murky Mississippi River.

The team of 15 divers and a five-member command crew arrived hours before dawn Tuesday, and several divers immediately entered the water even though local officials encouraged them to wait until daybreak.

"Two in the morning, they dove into the water," Minneapolis Police Capt. Mike Martin said, calling them "the best divers in the world."

Martin says it's so dangerous, at this point Navy divers are the only ones skilled enough to handle the search, reports CBS News correspondent Bianca Solarzano.

"The divers are facing extremely swift currents, experiencing very dark and deep places where lights aren't going to be able to help them see what they're doing," EMT Adam Wojciekhowski told Solarzano.

Navy Senior Chief David Nagle said the divers wanted to get a feel for the area, and were in the water for about two hours. Divers were back in the river by late morning, removing concrete rebar and other debris. Local crews have complained they have been hampered by dangerously unstable wreckage and a rapid current.

One of the cars that did tumble into the river was pulled out. No bodies were inside, but it's another step closer to getting searchers to the missing, reports Solarzano.

Hennepin County Sheriff's Capt. Bill Chandler said the vehicle was removed to make room for the Navy dive operation.

The team's arrival raised hopes of speeding up the recovery operation. At least eight people are missing and presumed dead in last week's collapse, with perhaps more still in the river. Five people are confirmed dead.

Joining the Navy team was an FBI dive crew, doing forensic work for the investigation. Their tools included a small unmanned submarine equipped with a robotic arm. "It's basically crime-lab-underwater kind of work," Martin said.

The Navy divers will be tethered to above-ground oxygen tanks, so they can stay in the water much longer than local divers, who had been using scuba tanks. Heavy-duty equipment will allow divers to cut through steel wreckage. The Navy also has sophisticated sonar to scan for bodies.

Navy divers assisted in the reclamation of historic sunken ships including the ironclad Civil War ship the Monitor. After the 1996 crash of TWA Flight 800 off Long Island near New York City, they made more than 700 dives to recover bodies and reclaim wreckage to help the government investigation. Navy divers recovered both the flight data recorder and the cockpit voice recorder.

Also Tuesday, four people still hospitalized with injuries from the collapse improved to serious condition, leaving only one person in critical condition. About 100 people were hurt in the disaster.

Separately, teams of designers and builders are racing to meet a dawn Wednesday deadline to show they are qualified to bid on a fast-track bridge replacement project.

State transportation officials hope to award contracts next month, with the goal of having a new bridge standing at the end of 2008.

Erecting such a bridge would ordinarily take about three years, even if the design and building phases were overlapped to save time, said Bill Cox, owner of Corman Construction Inc. in Annapolis Junction, Md., a road and bridge construction firm.

Teams of designers and builders are racing to meet a dawn Wednesday deadline for showing they are qualified to bid on the bridge replacement project, which the state has put on a fast track.

Minnesota Gov. Tim Pawlenty is reconsidering a proposed increase in the states gas tax to fund roads, something he's vetoed twice, reports Solarzano

State transportation officials hope to award contracts next month, with the goal of having a new bridge standing at the end of 2008.

A severe winter in a state known for its cold weather could throw off the reconstruction schedule. But other conditions are favorable — including a construction industry with plenty of available resources to take on such a daunting challenge.

"It is doable. It is a bit fast, but this is an emergency," said Khaled Mahmoud with the Bridge Engineering Association in New York. "And if we are ever good at anything, it's responding to emergencies."

The goal of awarding contracts in mid-September is highly ambitious given the array of questions to be answered, including whether to mimic the former bridge's alignment, how much traffic to accommodate, how much to spend and what it will look like.

The state intends to write financial incentives into the contract to make the compressed schedule more likely to be met.

The bridge's design will largely determine the cost, and although the federal government has pledged $250 million, Mahmoud said $300 million to $350 million "sounds about right."

One study estimates that more than 80 percent of the nation's roads and bridges are not capable of meeting the country's needs over the next decade. Rather than spending on needed repairs, much of the money spent goes to politically popular new projects, reports Solarzano.

Just last month, North Carolina opened this $102 million stretch of roadway, yet one in three bridges in the state is listed as substandard.

The city asked residents to observe a moment of silence Tuesday evening at the minute the bridge fell, and bells at churches and City Hall were to toll immediately after.

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