President Michael D Higgins has said he is shocked and saddened to learn of this morning's fatal fire in Dublin, and said: "This is a most dreadful tragedy."
Ten people, including children as young as six months, died in the blaze in Carrickmines.
Many people have commended the "heroic efforts" of the emergency services who risked their lives to rescue children from the blaze.
In a statement, President Higgins said: "My thoughts at this time are with the families and friends of those who have lost their lives and those who have been injured.
The Taoiseach said the loss of life as a result of the fire in Dublin was an "unspeakable tragedy".
Enda Kenny said he wished to join with President Higgins in expressing his sympathies on behalf of the Irish people to the relatives and friends of those who died.
He said the deaths of a husband and wife, their four sons and baby daughter along with other relations was a horrific tragedy.
Mr Kenny said his thoughts were with the bereaved.
He said there would be a full technical examination to ascertain the exact cause of the blaze and to identify how the fire spread.
But the Taoiseach said this would do nothing to ease the pain for relatives of the dead in coming to terms with what was a "tragic, horrible incident".
Taoiseach Enda Kenny has described this morning's fatal fire in Carrickmines in Dublin as an 'unspeakable tragedy' https://t.co/IGp78b1KLS
— RTÉ News (@rtenews) October 10, 2015
Speaking in Castlebar the Taoiseach said he had been contacted early this morning about the fire.
He said he had been in contact with ministers Alan Kelly and Alex White throughout the day.
Mr Kenny said emergency services responded very quickly and efficiently to the 999 call they received around 4:30am.
Tánaiste Joan Burton said: "I would like to express my deepest sympathies with the families of those who tragically lost their lives. I wish those injured the very best with their recovery."
Fianna Fáil leader Micheál Martin has said he is extremely shocked by the tragic fire that has claimed many lives.
Mr Martin expressed his "deepest sympathy to the families affected by this tragedy".
"I know our emergency services are working extremely hard in difficult circumstances since early this morning to deal with this incident and they are to be commended for their service," he added.
Sinn Féin President Gerry Adams has expressed his deep shock over the fatal fire.
Mr Adams said he wanted to commend the fire fighters and first responders who had been attending the scene, and to express condolences to the families and to all of those who are bereaved.
Minister Alex White expressed shock at the tragic loss of life.
In a statement, he said: "Our thoughts and prayers are with those who are currently battling with their injuries, and the families and friends of all those who died."
He also commended the "heroic efforts" of the emergency services.
Archbishop of Dublin Diarmuid Martin expressed his sympathy to the traveller families devastated by the fire.
Archbishop Martin said the news was heartbreaking for all in the traveller and wider local community.
He asked that the victims and their families be remembered in prayer at all Masses in the Archdiocese this weekend.
Fr Derek Farrell, Parish Priest of the Parish of the Traveling people in Dublin, is with the bereaved families.
Local Independent TD Shane Ross, who visited the scene of the fire, said it was an appalling tragedy.
He said there was a "numbness and silence" on Glenamuck Road South this morning.
Mr Ross, who lives close by, told RTÉ's Saturday with Claire Byrne it was an appalling scene, one of "desperation and despair".
Ronnie Fay, Co-Director of Pavee Point Travellers' Centre, offered her condolences to the families and friends of the victims on behalf of the centre.
"From talking to some of the families on the ground it seems to be an appalling tragedy we offer our condolences to the family and hope that they are being supported," she said.
"We know that the local traveller group on the ground in the area are offering good support to those families.
Ms Fay outlined the factors that led to overcrowding on some traveller halting sites.
"We do have a concern that overcrowding may have been an issue and many travellers because of lack of access to the private rented sector and we know that there is a very little housing available for anybody.
"We know that if you are a traveller it’s twice as hard, if overcrowding is a factor in this case it’s particularly tragic," she said.
