Six people are dead and another two still missing after a mining capsule fell out of control into a pit at an iron ore mine in Shandong province early Thursday morning, local authorities said.

The accident happened at 1 a.m. at the Shimen Iron Ore Mine in Lucheng township, Cangshan county of the city of Linyi when eight miners were working in the pit, according to the provincial safety supervisory department.

The number of the miners trapped in the capsule when the accident occurred was not known. The six miners died in a local hospital after being rescued from the pit.

An investigation into the cause of the accident is underway.

The privately-run Shimen Iron Ore Mine was once owned by the Jinan Iron and Steel Group.