An explosion hit a copper and zinc mine in Russia's central Orenburg Region, near the border with Kazakhstan, at 8:50am local time on Saturday.
There were 91 miners underground at the moment of the blast, which happened at a depth of 1.2km. Three people were killed, while 88 others were able to evacuate safely and obtain medical assistance, the local prosecutor’s office said.
The reasons for the incident at the Gaysky mining and processing plant are now being investigated.
A source told Interfax that the explosion took place during pyrotechnic works. A violation of safety regulations and a malfunctioning of gas sensors are being looked at as possible causes.