At least nine workers have died in a methane gas explosion at an Indonesian coal mine. A buddy was still missing on Friday, according to authorities in Sumatra Barat province (West Sumatra). Four miners survived the accident in the Sawahlunto district, some with severe burns, said Abdul Malik, head of the local search and rescue team.

According to a police spokesman, there have already been similar accidents in the mining area on the island of Sumatra. An explosion occurs when fine particles of coal dust come into contact with heat. The city of Sawahlunto was built in the 19th century by the then Dutch colonizers for coal mining.