Taoiseach Enda Kenny has offered the condolences of the Government and the Irish people to those affected by Sunday's Orlando gun attack in a letter to US president Barack Obama.
The attack on a gay nightclub in Orlando, Florida, which killed at least 50 people in the early hours of Sunday, has been described by the US president as the deadliest mass shooting in American history.
Mr Obama called the attack at Pulse nightclub “an act of terror and an act of hate”.
In a letter to the US president, Mr Kenny said Ireland was standing with the US "in this time of immeasurable grief".
“On behalf of the people and Government of Ireland, I offer our sincere condolences on the shocking loss of life in Orlando today,” wrote Mr Kenny.
"Our thoughts and prayers are with the people of the United States, the community in Orlando and the LGBT community, and above all with the families and loved ones of those so senselessly killed and injured.
“Once again we have witnessed the horror of young people being attacked as they enjoy themselves in their own community.
“Words cannot capture the shock and revulsion felt in Ireland, and around the world, at this outrage.”
President Michael D Higgins also sent his condolences to the families of the victims killed and injured in Sunday's attack.
Mr Higgins said he had spoken to US ambassador to Ireland Kevin O’Malley and had “personally conveyed my deepest sympathy and our nation’s solidarity with the people of the United States at this time.
"Our thoughts are with the people of Florida and the community in Orlando and Orange County at this difficult time," said Mr Higgins.
“The loss of innocent life on such a horrendous scale is truly shocking and challenges us all.”
‘Shock and horror’
Ireland’s Gay and Lesbian Equality Network (Glen) issued a statement on Sunday expressing their horror at the Orlando gun attack and offering their condolences to the families, loved ones and friends of the victims and survivors.
“We share the sense of shock and horror that so many people in Ireland are feeling as the news of the terrible events unfolds,” wrote Glen in a statement.
“We know that LGBT people in Ireland, their families, and Irish people generally, share the revulsion and horror at this awful attack and will decry hate crimes against LGBT people anywhere in the world.”
Catholic Archbishop Eamon Martin expressed his shock at the attacks and offered his prayers to those killed and injured in the shootings.
“The taking of innocent human life is always wrong,” said Archbishop Martin.
“On behalf of the Irish Catholic Bishops’ Conference I wish to express my profound condolences and I offer prayers of solidarity from Ireland to those who have been touched by this tragedy in the United States.”
Green Party leader Eamon Ryan condemned the attack, saying: “The violence committed against the LGBT community in Orlando is sickening. We echo president Obama’s sentiments that this was an act of terror and hate and must do everything we can to defeat this dreadful threat.
“We will succeed in the end by undermining this twisted narrative of hatred with a new understanding between the West and the Middle East.”
Sinn Féin leader Gerry Adams said in a statement: “I want to extend my sincerest and heartfelt sympathy and solidarity to the families and friends of those killed and the survivors of the despicable act of brutality and hate in Orlando yesterday.
“The Orlando shooting is a painful and harrowing reminder of the struggle for gay, lesbian and transgender equality the world over. My thoughts and prayers are with all of those affected at this time.”
Lord Mayor of Dublin Críona Ní Dhálaigh opened a book of condolence for the victims of the Orlando shootings on Sunday, which will be available for the public to sign from Monday-Wednesday of this week.
Members of the public are invited to sign the book between 11am-4pm on Monday, June 13th, between 10am-4pm on Tuesday, June 14th, and between 10am-4pm on Wednesday, June 15th.