The blaze broke out at the Dadong factory in the city of Wenling in Zhejiang province, state broadcaster CCTV said. Firefighters put it out about three hours later and rescued more than 20 people, it said.
The report didn't say how the fire started. Such factories often contain large amounts of adhesives and other flammable chemicals.
An official with the fire service in the surrounding city of Taizhou, who gave only his surname, Luo, confirmed the fire, but said he had no further details.
China suffers frequent industrial accidents and 121 people were killed in a poultry plant fire in the country's northeast last June. That fire was triggered by a short circuit, but investigators found the plant's safety exits were blocked, trapping workers inside.
On Saturday, a blaze raged for 10 hours in the heart of an ancient tourist town in the western province of Yunnan, destroying 242 structures and leaving about 2,600 people homeless. The severity of the fire was blamed in part on unresponsive firefighting systems and the inability of tanker trucks to enter the town's narrow streets.
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