Among the six people in police custody, four were suspected of "major liability in the accident" and two were suspected of "producing and selling shoddy products", local rescue headquarters said.
Further details of the suspects were not provided, state-run Xinhua news agency reported today.
A platform for a cooling tower being constructed as part of a power plant collapsed in Fengcheng city on November 24, killing 74 people.
Construction of the cooling tower was part of an expansion of Fengcheng Power Plant, which is owned by Jiangxi Ganneng.
Local police yesterday detained nine people in connection with the accident.
The arrested people include the chairman of Hebei Yineng Tower Engineering and the chief engineer of the construction project.