Authorities said Thursday they had recovered the bodies of two victims from the site of the interstate bridge collapse and believed they had a third. If the third recovery is confirmed, it would bring the confirmed death toll to eight.

One of the bodies was identified as Peter Joseph Hausmann, 47, of suburban Rosemount. Soon after Hausmann was found, Navy divers recovered other remains that were first thought to be one body. At a news conference, the Hennepin County medical examiner said that was now believed to be two people.

"The additional remains appear to probably represent more than one individual," said Andrew Baker, the county's chief medical examiner.

Hausmann was on a list of eight people that had been known missing in the Aug. 1 collapse. Baker said authorities believe they know the identities of the other two, and they were also on that list. They were not immediately identified.

All of the bodies were recovered in the debris field by Navy divers, who joined a slow-moving search for victims after it was nearly a week old, and they were expected to be in the water late into the night.

Sheriff Rich Stanek said that by Thursday, the Navy dive teams were able to penetrate most of the debris field — the collapsed bridge decking. He said there were a few of those spots left to penetrate, after which "some debris may have to be removed significantly before we make additional recoveries," Stanek said.

He said teams of the Navy dive teams have been working at the collapse site in 9-hour shifts, starting early in the morning and not wrapping up until late at night.

Baker said it may become more difficult to positively identify remains now that they've been in the water more than a week. He said his investigators have been working with families of the missing to get dental records and other medical information that could make identifications easier. He also said his office has access to DNA technology if that's needed.

The list of confirmed missing includes Christine Sacorafas, 45, of White Bear Lake; Vera Peck, 50, and her son Richard Chit, 20, both of Bloomington; Greg Jolstad, 45, of Mora; Sadiya Sahal, 23, of St. Paul, and her 2-year-old daughter, Hanah; and Scott Sathers, 29, of Maple Grove.

But authorities have warned that their list may be incomplete.

As searchers combed the river for victims, federal officials looking into the cause of the collapse issued an advisory for states to inspect the metal plates that hold girders together on bridges nationwide.

Investigators said the gussets on the failed Minneapolis bridge were originally attached with rivets, old technology that's more likely to slip than the bolts used in bridges today.

Some of the plates, or gussets, also may have been weakened by welding work over the years and some of them may have been too thin, engineering experts said Thursday.

Questions about the gussets prompted Transportation Secretary Mary Peters to caution states about stress placed on bridges during construction projects.

Investigators are also looking at whether extra weight from construction work could have affected the bridge. An 18-person crew had been working on the Interstate 35W span when it collapsed during the evening rush hour.

Bruce Magladry, director of the National Transportation Safety Board's Office of Highway Safety, said the agency will use a computer to simulate how the bridge might have behaved with different loads, and with different parts of the bridge failing. He said there are infinite combinations to test, so the simulation may have to be run 50 times or 5,000 times.

"Then we compare what the (simulated) collapse looks like to what we actually see out there on the ground," Magladry said, and repeat the simulation until it matches what happened.

NTSB investigators have been trying to pinpoint where on the bridge the collapse began. Observations from a helicopter camera this week found several "tensile fractures" in the superstructure on the north side of the bridge, but nothing that appeared to show where the collapse began, the NTSB said.

Also on Thursday, President Bush dismissed a proposal to raise the federal gasoline tax to repair the nation's bridges at least until Congress changes the way it spends highway money and considers the economic impact of a tax increase.

At the bridge site, recovery crews have removed several vehicles from the river in the last two days. In all, 88 vehicles have been located, both in the river and amid the broken concrete wreckage of the bridge.