JINAN - Three people have been killed and two others remain trapped after entering a gold mine in east China's Shandong province, local authorities said Thursday.

The accident occurred on Wednesday night, when five workers were lowered into a desolate gold mine belonging to the Rushan Jinhua Miming Company in the city of Rushan, according to a statement from the Rushan municipal government.

The workers drained water out of the shaft for 10 days before entering it to look into the possibility of discovering more gold there.

Three workers were lifted out of the shaft early Thursday morning but died after they were sent to a local hospital.

An initial investigation indicated that all three choked to death. But an autopsy is still needed to determine whether they were poisoned or suffocated from lack of oxygen, sources with the hospital said.

Rescuers are searching for the two workers who remain trapped.

An investigation into the accident is under way.