The fire broke out at a plant in Anyang City in Henan Province on Monday afternoon, news agency Xinhua reported.
Workers suspected of using welding equipment "against regulations" started the blaze, CCTV said.
The state media said rescue services first received reports of a fire at 4:22 p.m. at Kaixinda Trading Co., Ltd.
"After receiving the alarm, the municipal fire rescue detachment immediately dispatched forces to the scene," CCTV reported.
"Public security, emergency response, municipal administration, and power supply units rushed to the scene at the same time to carry out emergency handling and rescue work," it said, adding the fire was extinguished by around 11 p.m. local time.
Footage from the scene shared by state media showed thick plumes of black smoke from the fire, with at least two trucks in position to battle the flames.
Another video showed the charred hull of the building after the fire was extinguished.
In addition to the dead, two were sent to hospital with injuries that were not life-threatening, the state-run People's Daily said.
