MULLAN, Idaho ( AP) — Seven miners were safely removed from an underground mine in northern Idaho after they were injured by a rock burst while working more than a mile deep, a mine company official said late Wednesday.

One of the miners was taken to a hospital with nonlife threatening injuries, while the other six were treated at the scene, Hecla Mining Co. spokeswoman Melanie Hennessey said.

The miners were working about 5,900 feet underground when they were injured about 7: 40 p. m. by a rock burst, which is an explosion of rock caused by excessive pressure from the weight of the ground above. They were working in the Lucky Friday, one of the nation’s deepest underground mines.

Initial reports indicated that the miners could be trapped, but that wasn’t the case, Hennessey said.

The federal Mine Safety and Health Administration will investigate the incident, which comes after two Lucky Friday miners died in separate instances at the mine this year.

A roof collapse in a tunnel more than a mile underground trapped a 53-year-old silver miner in April. Crews recovered Larry Marek’s body nine days later.

Last month, miner Brandon Gray was buried in rubble after trying to dislodge a jammed rock bin. He died from his injuries two days later.