Six villagers in southwest China's Guizhou Province have been trapped in an abandoned antimony ore mine after being poisoned by toxic gas, local authorities said Thursday.

The accident happened early on Thursday in Dushan county in the Bouyei-Miao autonomous prefecture of Qiannan, when three local villagers entered the mine for illegal mining, said Yang Yongying, deputy head of the prefecture.

After the miners inhaled toxic gas and passed out, a villager posted as a lookout went back to the village and found two other locals for an attempted rescue. However, the three would-be rescuers were themselves poisoned and trapped after entering the mine.

Rescue work is under way and the incident is under investigation.