A brand new Pawan Hans’ Sikorsky chopper with 9 people on board crashed into the Arabian Sea, about 50 nautical miles from the Mumbai coast on Tuesday, killing four people -- including three ONGC employees.

The helicopter, was about 4-5 minutes away from its destination - ONGC’s Sagar Kiran rig - when the incident took place, company officials with direct knowledge of the matter said.

The chopper went down around 1145 hrs, just 1 nautical mile away from Sagar Kiran, but managed to stay afloat with the help of the attached floaters, helping rescuers pull out all the nine, including two pilots, after ONGC and Navy/Coast Guard scrambled in one of the fastest rescue missions in the western offshore.

Four of the nine pulled out were unconscious and airlifted in a Navy chopper to a hospital in Mumbai, where they were declared dead, an official said.

Three of the dead are employees of Oil and Natural Gas Corporation (ONGC), the state-owned firm which had hired helicopter service from Pawan Hans to support its oil and gas exploration and production operations in the western offshore.

The fourth person belongs to a contractor working for ONGC.The circumstances that led to the incident were not immediately known but western offshore had inclement weather and there was a swell in the sea.

Officials said ONGC has already instituted an inquiry into the incident.

The Directorate General of Civil Aviation (DGCA) is also likely to order a separate inquiry. Detailing sequence, officials said the chopper took off from Juhu helibase this morning just like any other day but 1 or 1.5 km from the landing zone on the rig, it went down into the sea.