FUZHOU, April 7 -- The blast at a chemical plant in China's southeastern Fujian Province on Monday evening was caused by fire at a xylene facility, an initial investigation revealed Tuesday.

According to investigators, a xylene facility leaked oil and caught fire, which led to blasts and a fire at three nearby oil storage tanks at Tenglong Aromatic Hydrocarbon (Zhangzhou) Co. Ltd. on the Gulei Peninsula in Zhangzhou City.

Nine experts were at the site to investigate in the accident.

Health authorities said six injured people are being treated in the hospital, while another 13 people had received medical examinations as of 7 a.m. Tuesday.

Environmental protection authorities have dispatched more than50 personnel to monitor the environment. Waste water has been collected and no excessive pollutants have been detected in three nearby villages.

Residents of the area have been evacuated and the fire has been contained. The fire department has sent 177 fire engines and 829 firefighters to battle the blaze.

This is the second accident in 20 months at the same facility, which produces paraxylene (PX), an industrial chemical used for making fiber and plastics.

PX plants are highly controversial in China, and proposed plants have met strong public opposition in recent years.

China's environmental minister urged during the country's annual parliamentary session in March that construction of PX projects pass environmental impact assessments.