Rescuers have recovered three bodies following the helicopter crash off Sumburgh yesterday.
Police Scotland has confirmed the news this morning and said a fourth person remains unaccounted for.
The families have been informed and further information will be released later.
Fourteen other people have been rescued and are in hospital.
A Super Puma L2 helicopter was carrying the men from the Borgsten Dolphin platform, east of Shetland, to Sumburgh when it ditched at about 6.20pm on Friday.
Several pieces of the damaged helicopter have been washed up against rocks near Garths Ness.
Serco NorthLink’s Hjaltland passenger ferry and cargo ship Helliar worked alongside Aith and Lerwick lifeboat crews to help in the rescue attempts. A Sea King helicopter landed at Clickimin last night carrying a “trauma team”.
First Minister Alex Salmond paid tribute to those involved in the rescue effort.
Mr Salmond said: “Our thoughts at this difficult time are with the families, friends and colleagues of those who lost their lives in this tragic incident. We also hope that those who were injured can make a full and speedy recovery.
“I would like to pay a massive tribute to all of those brave and hard-working individuals involved in the rescue effort and in treating the casualties when they were brought ashore.
“It is still too early to know what caused this terrible tragedy, but a full investigation by the relevant authorities is already under way. The Scottish government is in regular contact with all the agencies who have been involved in this rescue and recovery operation through our resilience process.”