A gas leak has killed at least 18 people working in a coal mine in central China, including the manager and others who attempted to save those trapped in the fumes, state media reported on Monday.
Another 37 miners were rescued and taken to a hospital for treatment following Sunday's accident at the Jilinqiao mine in Hunan province, according to Xinhua news agency, citing local authorities.
Investigators are testing the gas while police have detained an unspecified number of people in connection with the accident, Xinhua said.
Cai Yongheng, rescue team director, said rescuers had to carry oxygen tanks during the search for survivors.
A miner who declined to be named said after the mine manager was informed of the gas leak, he asked workers to enter to save their colleagues. Some of the rescue team, including the manager himself, were among those killed.
Another employee said a discontinued mine near the Jilinqiao had been discharging chemical waste gas, which may have triggered the fatal gas leak.
China is the world's largest coal producer and deadly accidents in mines are common.
Seventeen coal miners were killed when a lift used to move workers fell down a shaft in northeastern Heilongjiang province in March.
In December, explosions in two separate coal mines in the Inner Mongolia region and in Heilongjiang killed at least 59 people.