Four people choked to death after they inhaled a toxic gas in a pharmaceutical plant in Thane district yesterday, police said. At least five people were injured.

The accident happened in Sequent Scientific Ltd in Boisar around 7.30 pm when there were 17 people working in the plant.

"According to preliminary investigations, a pipe burst caused leakage of hydrogen sulphide gas in the plant premises," said Boisar Police Station in charge U D Sonawane.

While four who inhaled
the gas died shortly thereafter, at least five others were rushed to the local civil hospital, he said.

While two continue to remain critical, the other three are out of danger, according to Sonawane. The victims have been identified as Shivkant Tiwari, Binoo Sinh, Naresh Yadav and Sarvesh Kumar.

The plant is located in the Maharashtra Industrial Development Corporation's industrial area of Boisar and further investigations are on to find out the cause of the gas leak.