(CNN) -- A gas explosion Saturday killed at least 20 workers at a coal mine in central China, state media reported. Xinhua news agency earlier reported that 30 miners were trapped after the explosion in Henan province. The explosion comes after China announced this week that it had closed 1,355 small coal mines this year, according to Xinhua . The effort was part of a larger plan to restructure the mining industry to prevent deadly accidents and reduce greenhouse gas emissions, Xinhua reported, citing the National Energy Administration (NEA). China has one of the world's deadliest records for miners, with poor safety standards accounting for thousands of deaths each year. According to the China Mining Association, the goal is to eventually boost the industry. Small coal mines, which use outdated technology, will be replaced with larger coal mines, increasing capacity.
Dozens more still trapped, state media says . Blast comes after China moves to close many coal mines as part of a safety plan .