Palghar | A day after a nitrogen gas leak at a pharmaceutical factory in Maharashtra's Palghar district left four workers dead and two injured, police on Friday registered a case against the firm's four senior staffers, an official said.

An official from the Boisar police station said that the case has been registered against the senior employees of the pharma company under Bharatiya Nyaya Sanhita (BNS) section 105, which concerns “culpable homicide not amounting to murder”.

“They have been named in the FIR. The investigation is underway, and no arrests have been made so far,” the official said.

The incident took place on Thursday afternoon at Medley Pharma, located on plot number 13 of Boisar Industrial Estate, some 130 kilometres from Mumbai, according to the police.

Chief of Palghar district disaster management cell, Vivekanand Kadam, had told PTI that gas leaked from the nitrogen reaction tank at the pharma company between 2.30 pm and 3 pm, seriously affecting six workers.

"The six workers were rushed to Shinde hospital, where four of them died around 6.15 pm. They have been identified as Kalpesh Raut (43), Bengali Thakur (46), Dheeraj Prajapati (31), and Kamlesh Yadav (31). At the time of the incident, 36 workers were present in the plant," he said.

The condition of the two injured persons, Rohan Shinde (35) from Boisar and Nilesh Hadal (37) from Dahanu, is critical and they are being constantly monitored in the ICU, doctors at the facility had said on Thursday.

Local police and officials from the Directorate of Industrial Safety and Health visited the spot and began preliminary investigations.

“A probe is underway to see if there were lapses in safety protocols in place for such processes. The exact cause will be determined after technical assessment of the nitrogen tank,” another official had said.