A gas leak was the likely cause of a chemical plant blast Thursday afternoon in Tsitsihar City of northeast China's Heilongjiang Province, local authorities said Friday.

The explosion ripped through a nitrogen fertilizer workshop at around 5 p.m. Thursday in the chemical plant of Heilongjiang HeiHua Corporation, according to a spokesman with the local work and safety bureau.

Two workers were injured and rushed to hospital, said the spokesman.

There was no damage to the environment, according to test results from the city environmental protection bureau.