BEIJING (AP) -- Chinese authorities detained 13 people over the collapse of scaffolding at a power plant construction site that killed 74 workers, as a preliminary investigation zeroed in on how the building company had rushed the job.

Most of the dead had been working on the interior concrete wall of a massive circular cooling tower 70 meters (230 feet) up when the scaffolding collapsed Thursday morning, resulting in one of China's most serious industrial accidents in years. 

In a statement issued Saturday, the committee of the State Council, or China's cabinet, said early findings suggested that a shortened timeframe for the power plant project, hasty construction and mismanagement played a role in the disaster, without giving details.

Although authorities did not disclose details about the 13 detentions, the focus of the investigation has turned to the power plant's operator, Jiangxi Ganneng, and a major engineering firm, Hebei Yineng, which has taken on multiple high-profile power plant projects and has a history of workplace fatalities.

Yineng has won contracts to build plants in more than a dozen provinces and in Turkey and Malaysia, according to previous interviews given by executives. In 2012, seven Yineng builders in a cooling tower in Yunnan province tumbled to their deaths after scaffolding collapsed. Three years before that, two workers died after a vehicle accidentally backed into a scaffolding support beam at a Yineng-built cooling tower in Guangdong province.

Several of the company's publicly listed telephone lines and a mobile phone number for the company's legal representative rang unanswered on Friday. The company's websites could not be opened.

State media reports said the accident occurred during a change of work shifts, possibly accounting for the high death toll. Workers had also been toiling around-the-clock in three shifts to make progress on the project ahead of the arrival of bitter winter weather, according to local media interviews with surviving employees.

The 1,000-megawatt coal-fired plant had been designated a priority project by the province, likely adding to the pressure on workers. 

The deadly accident has taken on added political significance in recent days after Chinese President Xi Jinping urged local governments to hold those responsible accountable and the State Council established a special committee to investigate.

China has suffered several major work-safety accidents in recent years blamed on weak regulatory oversight, systemic corruption and pressure to boost production amid a slowing economy.