TAIYUAN -- Two people were found dead in a benzene tank truck Thursday, a day after the vehicle plunged into a river in North China's Shanxi province, local authorities said.

The tank truck carrying 25 tonnes of highly hazardous crude benzene broke through the guard rails of a bridge and plunged into the Fenhe River in Xinjiang county, Yuncheng city, after colliding with a bus on the bridge, according to the city government.

Benzene is a colorless carcinogenic compound used to manufacture plastics. It is known to damage blood production in humans.

The tank was pulled ashore Thursday afternoon after the benzene inside was transferred into another tank, removing a potential major pollution source for four counties downstream, the city government said.

A small amount of leakage was reported. Local environmental protection authorities are calculating the amount.

Local authorities in three counties downstream have built 31 lines of defence with activated carbon to absorb leaked benzene and prevent it from flowing into the Yellow River.