One crew member has been found after an Irish Coastguard helicopter with four people on board went missing off the west of Ireland.
A search is continuing for the other three crew from the Dublin-based aircraft, which was providing cover for another helicopter involved in an early morning rescue operation.
Contact was lost with the crew at around 1am.
An intense sea search is under way off the Co Mayo coast - around six miles west of Blacksod.
One casualty was located and plucked from the water at around 7am, according to the Department of Transport, Tourism and Sport.
The crew member, whose condition was described as critical, was taken to hospital.
Coastguard helicopters from Sligo and Shannon along with the Air Corps maritime patrol aircraft Casa were involved in the search.
They were joined by lifeboats from Ballyglass and Achill, and five local fishing vessels.
A Coastguard spokesman said the missing helicopter had been providing cover in the evacuation of a crewman who needed urgent medical attention, from a UK-registered fishing vessel approximately 150 miles west of Eagle Island in Co Mayo.
“Owing to the distance involved, safety and communication support, known as Top Cover, was provided by the second Coastguard helicopter, the Dublin based R116,” he said.
“The search operation is being coordinated by the Coastguard Rescue Coordination Centre in Malin Head.
“Both helicopters refuelled at Blacksod prior to transiting to the scene.”
Dublin’s Transport Minister Shane Ross expressed his “deep concern” over the helicopter’s disappearance.
He said: “As the search for the Dublin-based helicopter R116 is currently under way I would like to express my sincere support and sympathies for all those involved, particularly those family members who are awaiting news of their loved ones.
“This is an extremely difficult time for all concerned.”
Mr Ross appealed for space to be given to those involved in the search operation to complete their work.
“Once again, I send my utmost support to all those affected,” he added.