Five people choked to death after inhaling poisonous gas underground a pyrite mine in central China's Hunan Province Monday, local authorities said.

The accident happened at about 9:30 a.m. when a deputy mine manager and two workers went down a mine shaft to check the ventilation facilities, the county's publicity department said in a statement.

The mine is run by Yiyang Shengyuan Mining Co., Ltd in Taojiang County.

One of the three managed to escape after feeling uncomfortable due to the choking smell of the underground air, the statement said.

The other two died together with another three people who went down to rescue them, it said.

An investigation into the accident is under way.

The pyrite mine was ordered to suspend operation for rectification work in March and received a permit to resume production this month. But the mine was not operating as it needed further licenses from the firefighting, work safety and police authorities.