The Minnesota Department of Natural Resources says a fire in the state's oldest, deepest mine is 99 percent extinguished.
A three-man crew that made it to the bottom of the Soudan Mine in northern Minnesota Sunday afternoon didn't find an active fire.
The crew wore oxygen masks for their descent in the old iron mine's elevator at Soudan Underground Mine State Park. The mine caught fire Thursday.
Firefighters sprayed thousands of gallons of foam and water into the 2,300 foot-deep shaft.
Park spokeswoman Becca Manlove said the crew started critical sump pumps on levels 12 and 22.
She said they inspected the outside of the University of Minnesota physics lab on the mine's lowest level. Equipment in the lab has been valued at $100 million.
"We have not been able to get into the lab yet," she said. "We're very hopeful; it's not looking bad. There's not water on that level; there is foam."
Carson Berglund, a spokesman for the Minnesota Interagency Fire Center, said the team found items in the mine to be "not too badly damaged."
"Everything looks pretty good," Berglund said.
Manlove said officials won't officially declare the fire extinguished until they've found its source.
(The Associated Press contributed to this report.)