JINAN, July 17 -- A ferocious fire was put out 24 hours after it engulfed a petrochemical plant in east China's Shandong Province, according to the local fire control headquarters.

At 7:24 a.m. on Friday, more than 900 firefighters worked to extinguish the blaze which was caused by tanks leaking liquefied hydrocarbon, said a spokesman with headquarters.

Two firefighters sustained slight injuries, said the spokesman.

More than 5,000 residents living near the plant, in the city of Rizhao, were relocated to four settlements after safety concerns.

Monitoring results show air quality around the plant has come back to normal after excessive content of harmful non-methane hydrocarbon was found in some places on Thursday.

The plant processes heavy oils, with oil consumption of around 5 million tonnes per year.