FUZHOU, Feb. 4-- A poisonous gas leak left five workers dead in a wastewater treatment station of a thermal plant in Yong'an City in east China's Fujian Province Wednesday.

The accident happened around 10 a.m. when two workers were fixing the blowoff valve of a wastewater pool in a plant owned by the Fujian Fuwei Co. Ltd. Leaked hydrogen sulfide from the bottom of the pool poisoned the two workers and another three who were sent to rescue them, the local publicity department said.

The five workers died in hospital.

The cause of the accident is under investigation.