A gas leak occurred on an offshore oil rig, Sagar Uday, at Bombay High on Saturday, around 160km away from the city. Officials confirmed there were no casualties in the mishap.
The rig is one of many operated by the state-owned Oil and Natural Gas Corporation (ONGC) in the Bombay High area.
"Everything is under control and all the personnel have been evacuated. Our crisis management team is there," ONGC spokesperson Pallav Bhattacharya said.
ONGC was drilling a sidetrack well from a platform called NF on the Mumbai High North field.
"A gas pool was not expected at a shallow depth of 1,000 to 1,100m. But during drilling operations, some gas escaped and we have taken all precautionary measures," an ONGC official said.
According to initial reports, all drilling operations have been stopped for the time being and all non-essential staff has been evacuated.
ONGC evacuated employees by airlifting them by helicopters. Also, the Coast Guard and Indian Navy have diverted their ships to provide assistance in the evacuation operation.
There were a total of 110 employees at the rig when the incident occurred on Friday. Of these, at the time of going to press, only 20 from the crisis management team remain.
"The Coast Guard has sent its ship CGS Varun for assistance," said Coast Guard spokesperson, commandant Deepak Sharma. "Depending upon the situation, if needed, we will send more ships to assist in the rescue operation," he said.
ONGC sources said offshore supply vessels Great Ship SY Ramiya and MSV Samudra Pavah have also been deployed to assist the crisis management team.
The source said drilling operations were stopped and experts called in to control the gas flow.