The head of the coastguard says hopes are fading for three crew members of a missing rescue helicopter. One man has been located however is in a critical condition.
The coastguard has been giving a briefing in Dublin in the past hour - our reporter Sean Defoe was there.
The last communication from Rescue 116 was at quarter to one this morning when they were coming in to refuel at Blacksod after coming from Dublin.
They were due to head out to support Rescue 118 during a medevac operation when they disappeared from screens and communications.
There was no mayday call and as of yet we're unsure of what happened.
A search was then launched for the missing Rescue 116.
Debris has been spotted over a large range, and Director of the Coastguard Eugene Clonan says they're searching for the crew.
He's described it as a dark day for the emergency services.
The coastguard say the siskorski S-92 helicopters have a great safety record and while conditions were difficult last night they were flyable.
A large number of rescue vehicles are still on the scene off the west coast trying to find the missing crew members.