Five people died and one was injured Monday night when a crane collapsed in northwest China's Gansu Province, local authorities said Tuesday.

The accident occurred at about 11 p.m. in a wind power equipment company in Jiuquan, according to sources with the city's emergency relief office.

The arm of the crane broke and fell down during operation, instantly crushing five workers to death, according to the Jiuquan Administration of Work Safety.

The injured was in serious condition and sent to a nearby hospital, but his injuries were not life-threatening, the sources said.

An investigation into the cause of the accident is underway.