The Super Puma L2 aircraft was carrying 16 oil workers and two crew members from an offshore platform when it crashed Friday evening two miles west of the Sumburgh airport on Shetland, The Telegraph reported.
The oil workers were being transported from the Borgsten Dolphin Platform.
The dead were identified as Duncan Munro, 46, from Bishop Auckland; Sarah Darnley, 45, from Elgin; Gary McCrossan, 59, from Inverness and George Allison, 57, from Winchester.
The other 14 people, including the crew members, were rescued.
Jim Nicholson, a rescue coordinator with the Royal National Lifeboat Institution, said the wreck was below cliffs in an area with heavy tides.
A ferry headed to the Orkneys, a freighter and a fishing vessel were pressed into service to assist in the search for the missing.
The search was made more difficult by fog.
The incident raised questions about the safety of the Super Puma. Five of them have crashed in the last four years; Friday's crash was the second with fatalities.
One of the men rescued, Sam Smith, told his mother the helicopter lost power so quickly there was "no time to brace" and it "just dropped into the sea."
The helicopter's operator, Canadian company CHC, said it had suspended use of the aircraft pending an investigation.