At least four workers died and three others were injured after molten ore spewed from a furnace of a chemical plant in Gansu Province Tuesday, the local authority said Wednesday.

The injured at the hospital.

Ore being smelted in a huge furnace of the privately-run Huize Chemical Co. Ltd. gushed out at 4:20 p.m. Tuesday as the top layer of materials collapsed, said an official with the work safety supervision administration of Jingyuan County in Baiyin City, the site of the accident.

A stream of molten ore quickly spread out, leaving seven workers at the site seriously scalded.

Four of the workers died in hospital and three are still being treated.

An investigation team headed by the director of the provincial work safety watchdog was heading to the site, said Gou Xiaodi, an officer in charge of chemical products control with the bureau.