The Department of Transport is to begin an investigation after a member of the Irish Coast Guard died during a search operation yesterday.

Caitriona Lucas, a mother of two children, was killed after a rescue boat capsized in Kilkee, off the coast of Clare. 

The 41-year-old librarian was the first Coast Guard volunteer to die on duty. Her husband, Bernard, is also a member of the Doolin unit.

Two other crew members who were airlifted to safety remain in hospital today. One was recovered from the water and the other from a nearby cave area. 

Coast Guard manager Declan Geoghegan told Newstalk Breakfast that there is a "degree of trepidation" every time a rescue team is sent out, as "the slightest hitch in operation" can turn into tragedy.

"They were in the last leg of their search and they had radioed in that they were prepared to return home," he said.

"A couple minutes after that, they broadcast a mayday [emergency]. Whatever happened in those intervening minutes [is what] we have to establish."

Manual De Lucia, a member of Kilkee marine rescue service, said the news was difficult to take. 

"The whole area is devastated. We're a very tight-knight community.

"This is just so tragic. It will take a long time to get over."

'Ultimate sacrifice'

Taoiseach Enda Kenny yesterday led tributes to Caitriona, describing the work of Coast Guard volunteers as heroic and selfless.

"To learn of the death of Caitriona, and of injury to her colleagues, brings home the real dangers our rescue personnel face and this awful news casts a dark shadow over people all over the island," he said. 

"I want to convey my deepest sympathy to Caitriona's family; her husband Bernard, also a Coast Guard volunteer; and to the wider Coast Guard family."

County librarian Helen Walsh also paid tribute to Caitríona, who worked in branches at Ennistymon, Corofin and Lisdoonvarna for the past 16 years.

"This is a particularly difficult time for the library service, who recently lost another colleague," she said. 

The Coast Guard expressed its condolences to the Lucas family, and to all volunteers of the Doolin and Kilkee units.

President Michael D Higgins has also written to the family to extend his sympathies. 

In a statement, Minister for Transport Shane Ross said Caitriona "made the ultimate sacrifice" in her service to others. 

"Caitriona was a member of that extraordinary group of men and women who dedicate their skills, time and passion so that others may be safe on our coastlines.

"This is an appalling tragedy; the loss of a brave and valiant woman engaged in the most heroic of and unselfish of duties.

"Such remarkable courage and heroism in the service of others is rarely equalled and never surpassed."