Taoiseach Enda Kenny led Dáil expressions of sympathy with the dead and injured following the balcony collapse in Berkeley, California.

Mr Kenny said it was with great sadness he could confirm that a number of young Irish citizens had lost their lives, while a number of others were seriously injured.

He said the current information suggested all those involved were Irish.

"It is truly terrible to have such a serious and sad incident at the beginning of a summer of adventure and opportunity for so many young people on J1 visas in the United States, '' he added.

He said the Department of Foreign Affairs had opened its consular emergency response centre and an experienced consular team was ready to provide all possible assistance to the Irish citizens affected by the tragic incident and to their families.

The Irish consular general in San Francisco was in close contact with the authorities, he added.

Mr Kenny said he was shocked and saddened to hear of the tragedy.

“My heart breaks for the parents who lost children this morning and I can only imagine the fear in the hearts of other parents, who have children in California this summer, as they seek to contact them now,’’ he added.

The Taoiseach said the US ambassador Kevin O’Malley, who had many of the J1 visa holders in his residence before their departure, had telephoned to express his sadness and that of the US.

Fianna Fáil leader Micheal Martin said hearts and minds went out to the families and the parents in particular. Young people had their lives taken from them in their prime in the fullness and beauty of an American summer, he added.

“It is very, very sad news indeed,’’ he said.

Sinn Fein leader Gerry Adams and Independent TD Finian McGrath, on behalf of the technical group and fellow Independents, joined in the tributes.