Update: One of the tanks at a paraxylene chemical plant in China reignited three hours after the fire that raged in three tanks was put out. Firefighters stayed at the site of the accident overnight and kept spraying water on the tanks to reduce their temperature.

Six people were hospitalised and hundreds of firefighters deployed to fight a hydrocarbon fire following an explosion at a plant in southern China that produces the toxic chemical paraxylene.

Three gas tanks with a capacity of 20,000 cubic metres caught fire after the explosion. Authorities said there were no leaks from the plants three tanks of burning hydrocarbon liquids and no signs of contamination of the environment following the blast at Goure PX Plant in Zhangzhou, Fujian province.

Concerns over the safety of plants that make paraxylene, or PX, a chemical used for producing fibres and plastics, have prompted several protests in China in recent years. Exposure to the chemical can cause eye, nose and throat irritation.

Zhangzhou Deputy Mayor Zhang Yiteng told reporters that one person was injured at the blast site and five hurt by broken glass. Pictures posted by netizens on the Chinese equivalent of Twitter showing casualties were fake.

The official Xinhua news agency said strong tremors were felt up to 50 kilometres (30 miles) away.

Authorities deployed 177 fire trucks and 929 firefighters to fight the blaze and all nearby residents were evacuated, Zhang said. The fire was under control, and authorities were monitoring the environment for any contamination, he said.

This is the second accident in 20 months. There was an explosion at the factory, which belongs to the Tenglong Aromatic Hydrocarbon (Zhangzhou) Co Ltd, on July 30, 2013.

The plant attracted protests even before it was built. It was slated for the densely populated city of Xiamen in Fujian, but protests in 2007 by residents concerned about potential health hazards succeeded in getting it moved to a less populated area in Zhangzhou.