An explosion at an open pit coal mine in southeastern B.C. has sent three people to local hospitals with second- and third-degree burns.

"All employees, visitors and contractors at site have been accounted for. Three employees have received non-life-threatening injuries," said Teck Resources in a statement.

The company said a "flash fire" broke out around 10 a.m. PT in a dryer building at its Greenhills coal mine, about 35 kilometres north of Sparwood. It was quickly extinguished.

According to B.C. Ambulance Service, no one was in the room when the explosion happened. The three who were injured had been standing just outside the room.

Officials with B.C.'s Interior Health Authority say one person has since been released from hospital, while another has been flown by air ambulance to a Calgary-area hospital in serious but stable condition. The third person is still in a Sparwood hospital in serious but stable condition, waiting to be flown to Calgary as well.

There's no word yet on what caused the blast, but Teck Resources added that it had launched an investigation.

Meanwhile, the B.C. government says it has two inspectors en route to the site.

History of accidents

This isn't the first time there's been an accident at the Greenhills mine or at a Teck Resources operation.

In June 2010, four employees at the same mine had to be treated for smoke inhalation following a dryer explosion. At the time, Teck said the blast caused extensive damage to the building and forced a temporary shutdown of the mine.

In March 2014, an 59-year-old employee was killed in an accident at Teck's Coal Mountain Operations southeast of Sparwood. Miles Lorenz of Coleman, Alta., was filling his truck with water when a frozen rock fell from another vehicle and hit him.

The Vancouver-based company is one of Canada's largest publicly traded mining corporations. According to its website, the coal extracted at the Greenhills location is used to make steel.

MAP: Greenhills coal mine in Elkford, B.C.