Gas leaking from an oil refinery touched off explosions and a raging blaze that killed 25 people and injured 17 in Shanghai's worst fire since the Communists came to power, official media reported.

Saturday's blaze at the Shanghai Gaoqiao Oil Chemistry Corp.'s refinery occurred when "liquefied gas" leaked after a worker opened a water drain valve, the city's Liberation Daily newspaper said in its Sunday editions.The English-language China Daily said the fire was the worst in China's largest city since the Communists came to power in 1949.

A guard reported the leak about midnight Friday but nobody paid attention, the reports said. An hour later, the gas was ignited by sparks from a nearby construction workers' shed, touching off a fire that quickly spread back to the refinery, they said.

More than 400 firefighters rushed to the refinery area in the city 680 miles southwest of the capital to fight the blaze, which was extinguished in an hour, China Daily said.