Enda Kenny has said his thoughts are with the families of the brave crew of the Coast Guard helicopter which vanished off the Irish coast.
Speaking from the US, where he is to meet President Donald Trump at the White House, the Taoiseach was being kept up to date with developments off Blacksod, which is in his Mayo constituency.
“The Taoiseach is being briefed regularly here in the US on the Coast Guard helicopter accident that has taken place off the coast of Mayo,” his spokesman said.
“His thoughts are with the families of the brave crew and with the emergency crews currently working in the area.”
Transport Minister Shane Ross said he was deeply concerned about the incident and offered his 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,” he added.
Sinn Fein fisheries spokesman Martin Ferris paid tribute to the “selfless service” of the Coast Guard in saving countless lives.
“The rescue helicopters are a welcome sight, not just on the deck of a boat in trouble, but also to those injured and stranded on Ireland’s mountains,” he said.
“This has been a painful year for the Coast Guard, having lost their comrade Caitriona Lucas last September.”
Ms Lucas, a Coast Guard volunteer, died last September during the search for a missing man off the coast of Co Clare.
“This is testament to their bravery and dedication,” Mr Ferris said.
“My thoughts are with the families, comrades, and friends of the man recovered and those still to be found.”
Trade Union Impact, which represents the helicopter flight crew, also offered its support.
“The thoughts of all Impact members are with the families and colleagues of the crew of Rescue 116 as we await news from the search efforts,” a spokesman said.
A woman crew member from the Irish Coast Guard helicopter missing off the west of Ireland, who was pulled from the Atlantic but died, has been named as Captain Dara Fitzpatrick.