Relatives of those killed in the Omagh bombing have gathered to remember their loved ones 20 years after the explosion.
An inter-dominational remembrance service is taking place at the memorial garden in the Co Tyrone town.
Twenty-nine people, including a pregnant woman with twins, were killed in the car bomb ripped through Omagh on August 15, 1998.
The victims came from Northern Ireland, the Republic of Ireland, England and Spain.
The atrocity was claimed by a republican splinter group which called itself the Real IRA.
Police Service of Northern Ireland Chief Constable, George Hamilton, former Ombudsman Baroness Nuala O’Loan, and Ireland’s Health Minister Simon Harris, are among those attending the event.
Ireland’s premier Leo Varadkar and British Secretary of State Karen Bradley were both criticised for their decision not to attend the 20th anniversary.
In a statement, Ms Bradley said: “I would like to express my deepest sympathy to those affected by the devastating Omagh bombing ahead of the 20th anniversary this week.
“I hope today’s commemoration ceremony provides comfort to all those bereaved and is marked by hope and remembrance.
"We must never forget the loss that the victims of terrorism live with each day and the remarkable courage of all those affected by such unspeakable acts.”
The Omagh Community Youth Choir is performing a piece of music composed for the event by its musical director Daryl Simpson.
The choir includes Cara McGillion, 17, the daughter of Donna Marie and Garry who were left seriously injured in the attack.
Michael Gallagher, whose son Aiden was among those killed, paid tribute to all the victims of the 30-year Northern Ireland conflict, including the La Mon hotel IRA bombing which killed members of a local collie club in 1978.
The service included speeches from victims campaigners from the US and was attended by Police Service of Northern Ireland chief constable George Hamilton and a representative of the Irish Government, among others.
Relatives of the dead sat opposite the reflecting pool at the memorial garden, their garlands of flowers reflected in the pool.
A song was sung for Our Special Absent Friends.
Mr Gallagher said as a small province Northern Ireland was facing its greatest challenges ahead.
He called on the political parties to seek agreement “so that we can move forward”.
“Working alone we can achieve very little but in collaborative ventures we can achieve a great deal.”