ZHANGZHOU -- Firefighters in East China's Fujian province are working to prevent the chemical plant fire they put out for a third time early on Thursday from reigniting, more than two days after explosions rocked the site.

The blaze at Tenglong Aromatic Hydrocarbon (Zhangzhou) Co. Ltd. on Gulei Peninsula of Zhangzhou city was twice extinguished on Tuesday, but it reignited in both cases. Firefighters put it out again at 2:57 am on Thursday.

Large numbers of firemen are spraying water over storage tanks to cool them down.

There was an oil leak on Monday evening at the plant, which produces paraxylene (PX), used for making fiber and plastics. The oil caught fire, causing explosions at three nearby storage tanks.

The fire, which was put out for the first time around 4:40 pm on Tuesday, started again three hours later as residue in one of the three tanks ignited when exposed to the air.

At around 11:40 pm the same day, the fire was extinguished again, but was seen again at around 2:09 a.m. on Wednesday, according to the emergency response headquarters.

In addition, a fourth tank of nearly 1,500 tonnes of liquid hydrocarbon, caught fire on Wednesday morning.

Over 29,000 people have been evacuated from the surrounding area into temporary camps in logistics parks and schools in Zhangpu County.

"We're worried the fire is not properly out," said a resident of Youwo village of Gulei town.

Another villager surnamed Lin told Xinhua that he and his parents would stay with relatives in another city for a while.

The head of the provincial work safety department said a team sent to investigate the fire classified it as a "work safety incident". More details will be released after investigation.

Provincial environmental and marine affairs departments said no excessive pollutants have been detected in surrounding areas. Pollution monitoring is continuing.

The Tenglong plant covers about 115 hectares, including factories, a specialized wharf for oils and a thermal power station, according to its official website.

The Zhangzhou government had started to permanently relocate people living within 800 meters of the plant before the explosions. Some 10,500 people had moved to new homes by the end of 2014, said Shen Yongxiang, director of the management committee of Gulei economic development zone.

More than 400 people were still living in the area when the fire started, said Shen.

Known primarily for flower and fruit production, Zhangzhou has accelerated industrial development, especially of chemical works, in recent years, after seeing its neighboring cities of Xiamen and Quanzhou benefit from such a drive.

Gulei Peninsula, once famed for carrot production, is now among the seven biggest petrochemical industry bases in China.

Last year, Zhangzhou's gross domestic product grew 11.3 percent year on year to more than 250 billion yuan (about $40 billion). Its economic growth rate topped the list in Fujian for the first time in 52 years.