As U.S. Navy divers combed the gnarled wreckage of the collapsed Interstate 35W bridge Monday, federal agents used a robotic, arm-groping submarine, a helicopter equipped with cameras and detailed images being captured from scanners onshore to search for the missing.
But by rush hour - five days after the collapse - the exhaustive search still yielded no word on the fate of the eight people believed to have perished. Seven previously hidden vehicles were found in the Mississippi River and amid the rubble on Monday, authorities said.
Officials said six of the vehicles occupants' were accounted for either among the five victims whose bodies were already identified or among the dozens who made it out alive. But there was nothing found in a seventh vehicle known by police to have belonged to one of the missing.
"There (are) not easy ways to talk to the families about this stuff," said Hennepin County Sheriff Rich Stanek.
A strategy developed over the weekend has crews from a variety of agencies clearing debris and dumping it onto barges. The debris will then be reassembled at a location downriver so that authorities can investigate what may have caused the bridge to come apart.
Authorities hope as the debris thins, the site will yield clues to the fate of the missing. Searchers are also stationed downriver looking for bodies.
"I expect that things will start to move along pretty soon," Stanek said. "Bank to bank, our goal is to recover victims."
Meanwhile, federal investigators said Monday that they are focusing on whether a construction crew working on a bridge resurfacing project could have caused vibrations that destabilized the bridge.
State transportation authorities said two inches of concrete was taken off much of the bridge surface and then replaced. But in eight spots, all nine inches were removed and repaired because the surface needed it there. They refused to speculate whether the resurfacing of the spot repairs had anything to do with the collapse, leaving it to federal authorities to investigate.
"We're going to be looking at that entire area where the construction was being done," said Mark Rosenker, chairman of the National Transportation Safety Board.
On Monday, state officials indicated that as soon as the site is cleaned and combed in the coming days, it would be the focus of an intense, fast-track building of a new bridge.
As funding worked its way through Washington, officials said they hope to have a new bridge in place by late next year - about half the usual timetable.