CHENGDU -- The bodies of two people missing after a colliery gas explosion in southwest China's Sichuan Province were recovered on Thursday, bringing the death toll in Wednesday's accident to 13, local government said.

The victims were believed to have been killed by poisonous gas.

"We rushed to the scene and set up rescue teams. In the afternoon, about 30 rescuers went down the shaft and found the last victim," said Xiao Ronghua, Party Chief of Luxian County.

It is said 35 miners were working in the pit when the blast occurred Wednesday evening at the Xinglong Mine in Luxian County of Luzhou City. Twenty-two workers were being treated for injuries at a local hospital.

Investigators said the Xinglong mine was a legal, fully registered county-run mine with annual output of 60,000 tons.

An investigation into the cause of the accident is underway.