TOWER, Minn. (AP) - A $50-million physics laboratory operated by the University of Minnesota is being threatened by a fire burning deep in the Soudan Underground Mine State Park near Tower.

A spokesman for the Minnesota Interagency Fire Center, Carson Berglund, says timbers along the main mine shaft began burning Thursday night. There have been no injuries.

The fire is believed to be burning between the 23rd and 25th levels of the mine. The $50 million Soudan Underground Laboratory is on the 27th level, near the very bottom.

Berglund says the power has been turned off, which means the water that naturally drains into the bottom of the mine isn't being pumped out. If it gets high enough, it could flood the lab.

He says that could happen in one to two days.

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