"The Mississippi is notorious for undercurrents and swift water under the surface anyway," Fire Chief Jim Clack said, "and when you drop a bridge into it, with all its pieces, that creates ... whirlpools and things that are all dangerous to divers."

Two days after the Interstate 35W bridge dropped into the river amid evening rush hour, a fifth death was confirmed with about 100 injured.

Divers were looking for as few as eight people still reported missing. Initial estimates had put the missing at as many as 30. One woman turned up safe at work, Hennepin County Sheriff Rich Stanek said.

While the possibility of a lower death toll than first feared was good news, uncertainty about what they might find as they crawl through the wreckage has made the search psychologically draining.

"Nobody wants to find the carload of a family with small kids," said Sgt. Tony Waldo, head of the Ramsey County Sheriff's Department water patrol unit. "Nobody wants to find the family that was going to the Twins game that night."

The divers work in teams, with one or two in the water while tethered to a partner above for safety. They have stayed above the bridge's sunken span, avoiding the heavy debris below, officials said.

Friday's search focused on the upstream side of the bridge, while the U.S. Army Corps of Engineers regulated the water level to flow around seven feet, about two feet lower than normal, to try to alleviate the current's tug.

About 60 automobiles - partially or fully submerged - have been spotted around the giant chunks of concrete, broken steel and glass, Stanek said, adding that some vehicles are on top of one another. They cleared four cars Friday morning and found no bodies. A fifth was crushed beneath the others and couldn't be searched.