Two workers died following a gas leak at a factory in Khardaha near Kolkata, police said.
The incident happened during maintenance work at the plant of Electrosteel Castings Ltd (ECL) at B T Road in North 24 Parganas district, they said.
It is suspected that carbon monoxide gas leaked at the unit, leading to the death of two persons while another was taken ill, Barrackpore Police Commissioner Ajoy Thakur said after visiting the area.
The deceased were identified as Ranjit Singh (30) and Swapnadip Mukherjee (41).
Meanwhile, Rohit Mahato is critical and undergoing treatment at a hospital, police said.
The incident, which took place on Wednesday, sparked tension in the area with locals raising concerns about the safety measures at nearby factories.