At least eight people have died after a helicopter with 16 people on board crashed in the sea near Scotland.
The helicopter crashed at around 2pm on Wednesday, as it was flying people to Scotland from an oil rig.
Police say they've found eight bodies and are still looking for the other eight people who were known to be on board at the time of the crash.
The prime minister said: "My thoughts are with the relatives of those who have lost their lives in this crash."
Gordon Brown added: "It's at times like these that we remember the risks and the dangers that people have to undergo working to meet our energy needs."
The helicopter was carrying 14 people from the oil rig. The other two people on board were the pilots.
The head of the RNLI, Hugh Fogarty, said weather conditions in the area were believed to be good and that the sea isn't really cold at this time of year.
The people on board were all wearing special suits that should be able to keep them alive for hours if they survived the crash.