A vigil has taken place in Clonmel to remember the four victims of Friday night's crash and to express solidarity with their families.
Up to 2,000 people are estimated to have attended the event in Kickham Plaza near the centre of the town.
The single-vehicle crash on Friday night claimed the lives of Nicole Murphy, 18, from Ballypatrick; Zoey Coffey, 18, from Kilsheelan; Grace McSweeney, 18, and her 24-year-old brother Luke McSweeney, from Clonmel.
Nicole, Zoey and Grace had received their Leaving Cert results earlier on Friday and were being driven by Luke to meet friends in Clonmel for a planned trip to Carlow and a celebration event.
Tonight's vigil was led by local civic and religious leaders and among those who attended was the Bishop of Waterford and Lismore Alphonsus Cullinan who said he had received messages from around the country from people expressing their sorrow.
Mayor of Clonmel Richie Molloy addressed the vigil by saying that the tragedy was the worst in living memory.
He added: "It's very hard to know what the families are feeling this evening, and while we can imagine, it's very hard to know.
"All I can say as the mayor, the people of the town really want to show the families the feeling of unity that's out there."
Also in attendance were young people who were friends and former schoolmates of the four young victims of the crash.
Father Michael Toomey, a chaplain at CBS High School - which Luke McSweeney attended, said that people in the Clonmel area and around the country had been left speechless by the tragedy.
'A very tough few days and years ahead'
A cousin of two of the victims said that the family are facing "a very tough few days and years ahead" following their devastating loss.
At the vigil, Harry Phelan expressed his gratitude to the many who attended the event to show their sorrow and support.
Harry Phelan is a cousin of Grace and Luke McSweeney.
"Luke and Grace are my cousins, so it's extremely sad," he said. "It's a big shock. We're very close, we grew up with Luke and Grace and their siblings Mark and David, so it's very, very sad.
"A big shock, but it's great that the community in Clonmel came out this evening to support everyone."
Asked how the family are coping at the moment, he said: "Struggling, but they've really good people around them to support them and get them through.
"They can't really put into words and I suppose it hasn't really hit them yet, and it will be a very tough few days and years ahead."
At the close of the ceremony, many from the crowd lit candles and placed them at the back of the plaza area.
Meanwhile, flowers have been left at the spot on Mountain Road in Clonmel where the crash happened, outside the entrance to Hillview Sports Club, and around the corner on Raheen Road, close to the Loreto Convent which had been Nicole's secondary school.
Prayer services took place today at the Loreto Convent and the Presentation Secondary School where Zoey and Grace had been pupils.
The High School in Clonmel, where Luke McSweeney was a past pupil and where some of the victims still have siblings attending, opened up yesterday to allow students and families pay their respects.
Loreto principal Anne McGrath said teachers had welcomed their students with open arms this morning.
"They're welcoming their students in grief this time rather than in joy as we did on Friday," she told RTÉ's This Week programme.
"Those hugs were there on Friday in happiness [at the exam results], and today they're in consolation."
Ms McGrath said some of the students were on their way to Carlow to celebrate their exam results when they heard about the crash and returned home.
She said: "Some of the girls were already in Carlow, some were on the way.
"Some, ironically enough, we're playing a football match and were on the way by car and they just said to me that they just turned around.
"They came home, their parents supported them, and they wanted to be together.
"There was a lot of unknowns initially and it was very important that they were together, so that is what they have done since then ... That's how they've gotten through until now, because they can cry and grieve together.
"They know how each other is feeling."
Speaking on the same programme, Michael O'Loughlin, head of Presentation Secondary School, said the "devastation" of their deaths stretched beyond Clonmel to the whole Ballypatrick area.
He added there was a "huge interlink" between all the families affected.
"It's just heartbreaking to get the phone call on Friday night ... we were devastated," Mr O'Loughlin said.
"The news was so bad. There was no hope.
"And the communities of Clonmel have rallied around us, they've been great support, parents' emails, messages to the school, contacting us, coming into school and supporting us and that's what everybody needs now.
"The next few weeks are going be very tough for us all, but I know the Clonmel community will rally around us."
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This morning, at St Mary's Church in Irishtown, Clonmel, Fr Billy Meehan prayed at mass for the four young people.
Fr Meehan officiated at the wedding ceremony of Grace and Luke's parents, Bridget and Paul, and also baptised Grace and Luke in St Mary's Church.
"It's very difficult when you see on Friday morning they were all gathered above at the Presentation and Loreto celebrating their Leaving Cert results, a great sense of achievement and joy and celebration.
"Then 12 or 14 hours later it was all turned into devastation, sadness and sorrow, all their dreams shattered," Fr Meehan told RTÉ News.
He was one of the priests called by gardaí to the scene of the crash on Friday night.
Fr Meehan: "We anointed them and gave them absolution and then they were taken up to the hospital so then I went up to the hospital and gave a good few hours with the parents and families up there.
"It's devastating because there's so little you can do, but I suppose just your presence in being there, they know there's someone there with them, is a help to them.
"And hopefully in the months and years ahead that support will remain with them and they'll be able to pick up the pieces and carry on again with their lives."
