An explosion ripped through a mine in the coal-rich Kuzbass region of Siberia (search) on Wednesday, killing 17 workers and leaving nine missing, the government said.

The blast occurred at the Yesaulskaya mine (search) in the Kemerovo region, about 1,850 miles east of Moscow, said Olga Raskova of the Kemerovo government press service. Four miners were hospitalized with injuries but their lives were out of danger, she said.

Thirty miners were in the shaft when the explosion occurred, the press service said. Rescuers were searching for missing miners, Raskova said.

Seventeen miners were confirmed dead, said Sergei Vlasov of the Emergency Situations Ministry in Moscow.

Regional Governor Aman Tuleyev said blasts could still be heard in the shaft hours after the initial explosion, hampering rescue efforts.

The blast was caused by a methane build-up, according to a preliminary investigation. The press service said that smoke had been registered in the shaft on Tuesday night and that coal extraction had been stopped. The workers in the shaft at the time of the blast were trying to erect bulkheads to cut off the source of the smoke, the press service said.

Accidents are common in the Russian coal industry, which is plagued by dilapidated mines, aging equipment and safety violations. In the deadliest disaster last year, a methane blast killed 47 miners in the Kuzbass in April.