IRKUTSK, Russia -- Four Chinese workers were killed and five others injured Sunday in a fire that engulfed a wood factory in Russia's Far Eastern city of Zima.

The fire broke out in a makeshift wooden shelter of the China-Russia joint venture, which housed 33 Chinese workers, and spread to an area of 300 square meters, said Chinese Consul General in Irkutsk Guo Zhijun.

Investigators said the four dead were male, but their identities had yet to be determined.

Three of the five injured are in critical condition, while one worker is still missing, said Guo, who had rushed to Zima, in the south of the Irkutsk region, right after the accident.

Guo urged local authorities to find out the cause of the deadly fire and help to look for the missing worker.

Preliminary investigation showed the fire was triggered by an electrical fault.