Four people were killed while five others were injured after a helicopter crashed into the Arabian Sea about 50 nautical miles off the Mumbai coast. The helicopter, belonging to state-owned Pawan Hans and operated by the Oil and Natural Gas Corporation (ONGC), made an emergency landing on Tuesday morning due to rough weather. It was on its way to the Sagar Kiran rig when it fell into the sea about 1.6 kilometres from its destination. The helicopter, which was carrying two pilots and seven employees of the oil company, remained afloat for four hours. All nine passengers reportedly managed to inflate their life jackets before the helicopter hit the water. Indian navy and coastguard teams led the rescue operation. Four of the passengers were unconscious when they were pulled out of the stranded helicopter. They were taken to hospital but were declared dead soon after arrival, the ONGC said. The helicopter sank soon after the rescue mission and the oil company has launched an investigation into what led to the crash.