A rescue team are working to find a missing miner by clearing debris from a collapsed tunnel 6,150 feet underground at a northern Idaho silver mine.
Hecla Mining Company president Phil Baker said two employees were working near the collapse at the unfortunately-named Lucky Friday Mine, which happened on Friday afternoon, local time.
One worker escaped without injuries, but there has been no contact with the other, whose condition was unknown. The missing miner's name was not released.
"We are doing every effort possible to expedite this in a safe manner," said Melanie Hennessey, a company spokeswoman. "It is a rescue mission."
A 10-member rescue team was part of the rescue operation under way at the site in Mullan, a historic mining town of 840 people. Mr Baker said additional equipment was being flown in to allow crews to use a front-end loader to remotely dig away the material.
"We're securing the ground as we go," he said. "We're doing everything we can to reach the employee. We're just very concerned for the miner and his family right now."
Mike Dexter, another Hecla spokesman, said the two employees had just finished watering down blasted-out rock and ore when the collapse occurred about 75 feet from the end of the tunnel.
Officials say it is unclear if the entire 75 feet collapsed, or only a portion of it, possibly leaving the miner trapped on the other side.
The mine employs around 275 workers, about 50 of whom were underground in various locations of the mine when the collapse occurred, said Ms Hennessey.
On its website, Hecla describes itself as the oldest US-based precious metals mining company in North America and the largest silver producer in the US Its headquarters are in Coeur d'Alene, Idaho.