An explosion at a coal mine in China killed at least 82 people in the country’s deadliest mining accident in years.

China is the world’s largest coal producer — last year it accounted for more than half of global output — even as it rapidly expands its renewable energy buildout. Coal has helped Beijing weather the energy shock brought on by the Iran war.

While the government has stepped up inspections and safety oversight in recent years, reducing fatalities, the gas explosion on Friday night is “raising uncomfortable questions” about the extent of China’s efforts to promote energy security, Bloomberg wrote.

Any crackdown risks threatening coal output at a precarious time.