It is ten years since the Real IRA bombing in Omagh, which killed 29 people, including a woman pregnant with twins.
The attack in Co Tyrone, which took place four months after the signing of the historic Good Friday peace agreement, was the bloodiest single incident of the Troubles.
The failure to catch the killers has seen police on both sides of the border heavily criticised for their handling of the investigation.
Watch how RTÉ News reported the bombing in 1998
Read a timeline of events leading up the attack
Leave YOUR comment on the 10th anniversary of the atrocity
Prime Time looks at the handling of the Omagh bomb investigation
The victims were:
James Barker, 12, Buncrana, Co Donegal. (Originally from Surrey)
Fernando Blasco Baselga, 12, Madrid, Spain.
Geraldine Breslin, 43, Omagh.
Deborah-Ann Cartwright, 20, Omagh.
Gareth Conway, 18, Carrickmore, Co Tyrone.
Breda Devine, 20 months, Donemana, Co Tyrone.
Oran Doherty, 8, Buncrana, Co Donegal.
Aiden Gallagher, 21, Omagh.
Esther Gibson, 36, Beragh, Co Tyrone.
Mary Grimes, 65, Beragh, Co Tyrone.
Olive Hawkes, 60, Omagh.
Julia Hughes, 21, Omagh.
Brenda Logue, 17, Omagh.
Ann McCombe, 45, Omagh.
Brian McCrory, 54, Omagh.
Samantha McFarland, 17, Omagh.
Sean McGrath, 61, Omagh.
Sean McLoughlin, 12, Buncrana, Co Donegal.
Jolene Marlow, 17, Omagh.
Avril Monaghan, 30, Augher, Co Tyrone (pregnant with twins).
Maura Monaghan, 18 months, Augher, Co Tyrone.
Alan Radford, 16, Omagh, Co Tyrone.
Rocio Abad Ramos, 23, Madrid, Spain.
Elizabeth Rush, 57, Omagh.
Veda Short, 46, Omagh.
Philomena Skelton, 39, Drumquin, Co Tyrone.
Fred White, 60, Omagh.
Bryan White, 27, Omagh.
Lorraine Wilson, 15, Omagh.
Within seconds of the bomb exploding, the largest emergency operation in Northern Ireland's history got under way.
21 people died instantly but more than 300 others lay injured in the rubble of Market Street.
Less than 1km away, staff at the Tyrone County Hospital would soon be swamped with casualties and relatives frantically looking for missing loved ones.
Ten years on, four of those involved at the explosion site and the hospital relive their experiences.
Tony McLaughlin, 54.
Now retired, Tony McLoughlin was a paramedic in the first ambulance to arrive at the scene minutes after the bomb went off.
'There was this massive pile in the middle of the road where the shops had been tumbled out and there was bodies lying everywhere.
'We drove up and parked at Slevin's chemist, right beside the bomb. When we saw the massive scale of the thing we got on the radio right away and said 'Jesus get as many people here as you can, as many ambulances here as you can'.
'We got out of the ambulance to get a quick survey and there was a police sergeant on top of the pile and he shouted 'Tony this is massive, we need more help'.
'I went back to the radio again but when I got back to the radio the ambulance was full of people, people had started to carry them in straight away.
'There was a wee boy standing there crying and my partner John lifted him and his leg was just sliced off. We lifted him and his leg just stood there.
'When I got back to the scene people were using boards, using doors, using anything at all to put people on and out them in pick ups, put them in anything at all. The work was made lighter for us because the people there at the time they used cars, picks ups, anything at all to bring them up to casualty. There were buses brining them up too. It was a constant flow.
'Casualty was unreal. The blood was actually running out of the doors. The consultants were in then but there was no way they could see all the people, the amount of people, they were lined up corridors.
'At the time you just had to concentrate on what you were doing. You should never have been asked to do what we did that day but I mean it had to be done, the people needed help.'
Paddy Magowan, 71.
Paddy Magowan was a part-time firefighter and district manager of Omagh Ulsterbus station in 1998. The local councillor had been driving in toward the town centre when the bomb went off.
He was one of the first people to arrive at the scene.
'There was no ambulance by that stage, no fire brigade, nothing but the people and they were all running and screaming and injured, terribly injured and of course dying and of course death at first hand.
'I had been a fireman for 25 years and I had seen carnage at first hand believe you me I had collected bodies of soldiers and pieces of flesh and pieces of men, different heads and arms and you name it in bombs here. but that day was unimaginable.
'People kept shouting at me 'What are we going to do, what are we going to do?!".
'At that moment when I lifted my head from what we were working on on the street I saw a bus just in front of us, just in front of the tragedy and where the bomb had gone off.
'The people were standing up and bleeding and they were terribly injured and I said 'put them on the bus'. So everybody helped everybody get on. Some people had lost limbs and they were put on the bus with them.
'It was absolutely horrendous. I remember myself and a young chap who worked in one of the hardware stores, him and I sort of working in a wee team together and there was this duvet cover and I said 'we'll cover up people with this'.
'I ran over to the lift it and when I rolled it back there was a dead baby there, somebody had already rolled a wee dead baby up in it.'
Peter Garrett, 55.
Dr Garrett was on-call at the Tyrone County Hospital that Saturday.
He lived around 10km outside the town. If a major incident occurred it was his job to put the emergency response plan into operation.
'I was at home late lunchtime and just relaxing when a call came through from the switchboard that there was a major emergency and to come in immediately.
'To be honest I almost certainly thought this was a dry run (of the emergency action plan) because we had had a dry run that Monday which interestingly enough had demonstrated some problems with our system, which we had then rectified.
'At the hospital I just discovered a really horrific scene. First thing I saw when I got to the hospital was an Ulsterbus single decker parked outside Accident and Emergency.
'My first thought was because the last disaster that happened in these parts was the bomb in Ballygawley (in 1988), and there was a bus involved in that, I thought maybe there was a bomb on the bus and they had just driven it straight here.
'A&E was covered in blood, the floor was covered in blood, it was a scene of carnage with very severely damaged young people undergoing resuscitation procedures.
'There were many fatalities at the scene and a number of patients arrived at the hospital already dead. But we lost only two cases who had arrived alive in the hospital. I think that is very strong testament to the quality of work that went on.
'The severity of the injuries suffered by both the fatalities and the injured were very, very great and quite horrifying. It was very difficult for the many members of staff who were not used to dealing with trauma, many of these people had come from all around and helped out.
'What was absolutely horrifying was the fact that Omagh is such a small town and the people who were directly involved were known to very many of the staff. Also that so many of the them were young people, at least half the fatalities were youngsters and teenagers just starting out in life, and that was certainly very difficult for everybody to deal with.'
Dominic Pinto, 71.
Now retired, Mr Pinto was the senior surgeon at the Tyrone County Hospital. He was playing golf with his son at the nearby Omagh Golf Club when he heard the explosion. Without waiting for a call he headed straight to the hospital.
'It was just like a battlefield, they were everywhere, along the corridors, on the floor, you just can't describe it, people were just pouring in.
I believe there was a bus, somebody commandeered the Ulsterbus, which is only next door to where it happened.
The bomb was literally about three quarters of a mile so there was walking wounded as well. It was initially pandemonium.
'But fortunately this was the people of Omagh and this was their hospital and the nurses and doctors who were looking after them were family and friends.
'So yes, there was panic at the beginning but everyone listened to what you had to say and we were able to control it very quickly. As I was the senior surgeon the first thing was to prioritise because I could see there were injuries that had to be sent somewhere else.
'A number of people had died at the scene. Of the injured at the hospital you had a lot of lower limb injuries, a lot of shrapnel injures, some to the chest. We had a lot of limb injuries but we had severe abdominal injuries too and head injuries.
'The thing was, you actually saw people who you knew and they were looking to you and saying what are you doing for me?
'In a professional way you couldn't get involved, you had to get down professionally and deal with whatever was needed at the time. It's only on reflection that you realise there were very close friends of mine there. One who lost a child, the other was badly injured. At the time you just had to get on with it.
'I was operating 'til well after ten 11 o'clock at night, straight through. But the abiding memory I have is having worked in theatre I came out and just went round the ward.
'When I first arrived it was like a battlefield, people and blood everywhere. And when I went round at 10.30/11 I was surprised how quiet it was. Eerily quiet. And the most important thing was the hospital was sprucelessly clean, wherever we had been before, from casualty onwards, you'd never know anything had happened - it was that clean. That was great credit to all the people in the hospital who came in to help.'