Rescue officials in Canada are working to free three miners who are trapped underground in northern British Columbia after a mine collapse.

The trio were working at the Red Chris mine on Tahltan Nation territory, 260 miles (420km) west of the town of Fort Nelson.

“There was an accident,” British Columbia Premier David Eby said on Wednesday. “There are three miners that are currently trapped underground. They are, to the best of our knowledge, uninjured and in a refuge area.”

An area of ground in the mine collapsed the previous day near an area in which the group were working, mine operator Newmont Corp said in a statement.

The miners – two of whom are from British Columbia and one from Ontario – were able to move to a sealed area underground, before a second collapse further blocked their movement, Newmont said.

The area where they relocated included a refuge station that had adequate food, water and ventilation to “support an extended stay”, the operator said.

“At the time of the initial incident, three business partner employees were working more than 500 meters beyond the affected zone and were asked to relocate to a designated refuge station before a subsequent fall of ground blocked the access way,” Newmont added.

Since the second collapse, there has been restricted communication, so a “standdown of operations” at the mine is in place, the company said.

The mine in which the three are trapped is an open-pit copper and gold mine, which was constructed in 2014.