The fire Tuesday occurred at the factory making underwear in the city of Shantou and that a suspect was being held, Xinhua News Agency reported.
A caption on a photograph of the factory building said all the victims were women.
One more person was injured in the blaze, and had been taken to a hospital, Xinhua said. The condition of the person was not immediately known.
The report, quoting local authorities, said a preliminary investigation indicated the fire might have been the work of an arsonist.