A fire that broke out at a chemical factory in Lengshuijiang, Central China's Hunan Province, on Saturday night may have put the local environment in danger, environmentalists said.

Volunteers from Green Hunan, a Chinese environmental protection NGO, posted pictures on their official WeChat account of wastewater from firefighting being discharged into a nearby river without proper treatment.

Volunteers who ran preliminary tests on the wastewater have found it to be highly alkaline. It was unknown whether the pollution came from the chemical factory or the firefighting material.

The fire started with blasts felt throughout the local area at 8:20 pm and was put out two hours later, reported Beijing-based newspaper the Legal Mirror.

No casualties were reported, and residents have been evacuated from the area for fear of potential health hazards.

According to the Legal Mirror, the chemical warehouse that caught fire belongs to Hunan Lengshuijiang Hengxing Chemical Auxiliaries Co Ltd, which specializes in producing PVC-based plastics products.

Company manager Yang Cheng told the Global Times on Sunday that the company had already halted production at the factory in May.

Yang said the fire was caused by faulty wiring that had degraded after months of disuse and had been aggravated by recent wet weather.