Seven people were confirmed dead and six others were missing in a coal mine explosion in northwest China's Ningxia Hui Autonomous Region late Wednesday afternoon, the local government said early Thursday.

The accident happened at around 6:20 p.m. at Dafeng Mine in the city of Shizuishan, when workers from a local mechanical-chemical firm were using dynamites to blast away rocks in one of the mining areas.

Four people were killed on the spot and three others died at hospital Wednesday night, a spokesman with the city government said.

As of Thursday morning, six people remained missing and two others were in hospital with serious injuries.

Rescue work is continuing and the regional government has launched an investigation.

A similar tragedy was reported at the same mine in October last year, in which 16 people died and 48 were injured.

Dafeng Mine is owned by Shenhua Group, one of China's mining giants.