At least 800 firefighters and 170 fire engines are at a chemical plant in the city of Zhangzhou.
Firemen are battling the third in a series of blazes that began on Monday, when an oil leak caught fire and spread to nearby tanks.
More than 14,000 residents in the surrounding area have been evacuated, reported state news agency Xinhua.
Six people have been hospitalised for minor injuries, while 13 are receiving medical attention, said CCTV.
Xinhua said the fire began on Monday evening when an oil leak caught fire and led to blasts at three nearby oil storage tanks at the Tenglong Aromatic Hydrocarbon plant in Zhangzhou.
That fire was extinguished on Tuesday afternoon. It reignited that evening before it was put out again.
But another tank containing nearly 1,500 tonnes of hydrocarbon liquid caught fire and exploded early on Wednesday morning.
The plant produces the chemical paraxylene which is used for fibre and plastics.
Authorities said that the fires were reigniting due to residue being exposed to the air.
Experts interviewed by Xinhua said that the layer of foam sprayed by firefighters to cover the residue was becoming unstable due to the heat and was disintegrating, and was being shifted by strong winds.
Thousands have been evacuated in the southern Chinese province of Fujian as a massive chemical oil fire reignited.