Some shocking pictures have emerged, showing how the work platform attached to the cooling tower being built at a power plant in Fengcheng, China, gave way at about 7.30am (local time).
One person has been confirmed missing by state media, two others are injured.
Iron pipes and wooden planks can be seen strewn across the floor of the massive concrete cooling tower in television footage.
Search dogs have been rushed in to aid the rescue operation.
Rescue workers dug through the debris with their bare hands in desperate attempt to find survivors.
China has suffered a string of industrial site accidents in recent months.
