Rescue workers in neon jumpsuits carried bodies out from the site on stretchers wrapped in orange sheeting.
At least 40 people were killed when part of a power station under construction in China collapsed Thursday, the official Xinhua news agency reported, the latest industrial accident in a country with a dismal safety record.
A cooling tower platform plunged to the ground in the early hours, trapping an unknown number of people beneath it, Xinhua said.
Pictures of the scene in Fengcheng, in the central province of Jiangxi, showed a grey mass of concrete slabs, steel girders and twisted metal splayed in a heap on the ground inside a large round structure.
Hard-hatted rescue workers in neon jumpsuits carried bodies out from the site on stretchers wrapped in orange sheeting.
Rescue work was underway, and a total of 32 firetrucks and 212 military personnel had been deployed to the scene, the Jiangxi provincial fire department said on a verified social media account.
Xinhua earlier said more than 40 people had been confirmed dead, before correcting its report to 40, adding: "It is likely to rise as an unknown number of people are still trapped."
Five injured workers were being treated in hospital, it said.
Around 68 people were on site when the collapse occurred, according to local state media outlet China Jiangxi Online.
The construction of two 1,000-megawatt coal-fired power units at the Ganneng Fengcheng power station began last July and were expected to be completed by early 2018, the local Yichun city government said on a verified social media account last year.
The expansion project cost a total of 7.67 billion yuan (now $1.1 billion), it added.
Industrial accidents are common in China, where safety standards are often laxly enforced.
In August a pipeline explosion at a coal-fired power plant in the neighbouring province of Hubei killed 21.
Earlier this summer more than 130 people were taken to hospital after chemicals leaked from a plant in eastern China.
In April a chemical fire burned for 16 hours in the coastal province of Jiangsu after an explosion at a facility storing chemicals and fuel, requiring 400 firefighters to quell the flames.