Eight miners were confirmed dead and at least 20 injured on Friday morning in a methane gas explosion at a coal mine near the town of Sokobanja in Serbia.

Local media reported that the explosion happened at 5 am, bringing down parts of the mine shaft and leaving some miners trapped. Belgrade daily Vecernje Novosti said that at least 20 miners were trapped by the blast, adding that efforts are now underway to rescue them.

Serbian state broadcaster RTS quoted the head of the medical center at nearby Aleksinac, some 170 kilometers south of Belgrade, who confirmed the deaths and injuries, adding that injured miners were also being taken to other medical facilities in the area.

The town’s emergency services sent four medical teams to help treat injured workers at the mine. The miners who were in the shaft at the time of the methane explosion were reportedly all from Aleksinac.

The Soko coal mine is located near the spa town of Sokobanja, and has a long history of mining, dating back to 1908. This was not the first serious incident at the mine, as a similar gas explosion killed 29 miners there in 1998.

The mine is owned and operated by the state-owned company Resavica, which runs nine coal mines in the country and employs around 4,000 workers.