An Irish Government minister has travelled to the US to give first hand support to the grieving families of six students killed in a balcony collapse.
The first groups of parents arrived in San Francisco overnight to begin the unenviable task of visiting hospitals and mortuary rooms where their sons and daughters lie.
The victims - five from Ireland and one from California - plunged from a fourth-floor apartment in the university city of Berkeley as they attended a 21st birthday party in the early hours of Tuesday.
Foreign Affairs Minister Charlie Flanagan said concerns were also turning to the impact the trauma will have on those who survived the accident and those who witnessed it.
"We are also conscious that many Irish students were not physically injured, but were left deeply shocked and saddened by the loss of friends and classmates in this terrible accident," he said.
Seven people remain in hospital in California, some critically ill.
The close connections between all the dead and injured - friendships which spanned south Dublin suburbs, old school links and university classes - prompted a raw outpouring of grief at home.
The dead were were Ashley Donohoe, 22, an Irish-American from Rohnert Park, a city north of San Francisco, and her 21-year-old cousin Eimear Walsh, from Foxrock, south Dublin.
Ms Walsh studied medicine at University College Dublin (UCD), as did Lorcan Miller, also from south Dublin who was described by former teachers at St Andrew's College Booterstown as an exceptional person and perfectly suited to his chosen career as a doctor.
Headmaster Peter Fraser recalled him.
"The one thing speaking to colleagues this morning was the fact that he was positive, engaging, a decent boy who was incredibly talented, but normal, modest and balanced about it all. He was hugely popular," Mr Fraser said.
Niccolai Schuster, from Terenure in the Irish capital, was also at UCD and studying history and politics.
Another link was the death of Olivia Burke, also from south Dublin, and Ms Walsh's friend from their school days in Loreto College Foxrock. She studied at Dun Laoghaire Institute of Art, Design and Technology.
Bernadette Prendiville, principal at Loreto, said: "They were just two beautiful students."
Eoghan Culligan, a student at Dublin Institute of Technology, was a passionate gaelic footballer and had gone to St Mary's College in Rathmines, Dublin with Niccolai Schuster.
They were all 21 and in the US on J1 working visas for the summer, a rite of passage for young people at college in Ireland.
Books of condolences were being opened in the Mansion House and St Patrick's Cathedral in Dublin, also in Cork and Galway while an online version on the UCD website was inundated with more than 8,000 messages in a few hours.
The Irish Tricolour flew at half mast at Government Buildings in Dublin while Ireland's Dail parliament held a minute's silence and suspended normal business as a mark of respect.
Taoiseach Enda Kenny said: "We've all been shocked by the loss of life and injured.
"It is a terrible situation to have such a serious and sad incident to take place at the beginning of a summer's activity and opportunity for so many young people on J1 visas in the US."
Jimmy Deenihan, the minister responsible for diaspora affairs, was sent to San Francisco in a sign of solidarity while UCD also sent its chaplain, John McInerney, and a senior student services employee to help students.
An incident centre has been set up in Berkeley City Hall as officials await the first reports from police, fire and engineering investigations to determine the cause of the accident.
While prayers were offered around Ireland, the Catholic Bishop of Oakland, California Michael Barber talked to Ireland's senior Catholic cleric Archbishop Eamon Martin and held a memorial mass.
Some 24 hours since the tragedy, questions are moving on to the cause of the accident, with engineering crews expected to continue examining broken wooden beams which held up the balcony.
Investigators said the building code for 2007, when the property was completed, would have included a 60lbs-per-square-foot rule for the balcony, and with 13 people on the structure it may have been overloaded.
The Library Gardens apartment complex on Kittredge Street in Berkeley - a popular building for Irish students in the city for the summer and two blocks from the University of California, Berkeley - was built with a wooden frame.
Investigations will also examine if the cantilevered structure had been affected by dry rot or water damage. City inspectors "red-tagged" the rest of the building's balconies after the accident, banning their use.
Some 700 Irish students are in the San Francisco Bay Area for the season.
Police confirmed they had initially received reports of noise from the party about 45 minutes before the tragic accident, but officers had to divert to reports of a shooting elsewhere in the city.