Three workers died and six others were injured in east China's Shandong Province on Monday, when a furnace used to produce raw materials for aluminum collapsed, local officials said.

The accident took place at about 11 a.m. in Pingyin County in the suburbs of Jinan, capital of Shandong, as nine workers attempted to dismantle an in-ground furnace that produced pre-baked anode cells, which are the raw materials for aluminum.

The isolation walls of the furnace toppled, burying all nine workers. The furnace, which had been offline for more than two months, was owned by a private firm based in Kongcun Township, the officials said.

Two of the victims were pronounced dead at the scene and a third died during surgery.

The injured, two of whom were in serious condition, remain hospitalized.

Local authorities are investigating the cause of the accident.