Relatives of 11 people killed in an IRA Poppy Day bomb in Enniskillen will gather to mark the 25th anniversary of the attack on Thursday.
A special memorial service is being held for survivors and relatives of those who died in the town in Co Fermanagh, Northern Ireland.
Stormont First Minister Peter Robinson and Northern Ireland Secretary Theresa May are expected to attend.
Eleven people were killed and 63 others injured when the no-warning bomb ripped through the Co Fermanagh town on November 8, 1987.
A 12th victim, school principal Ronnie Hill, spent 13 years in a coma and died in 2000.
No-one has been convicted in connection with the explosion at the town's cenotaph shortly before a Remembrance Sunday ceremony.
A service will be held at St Macartin's Church of Ireland Cathedral in Enniskillen and there will be a wreath laying ceremony at a war memorial in the town.
A new file on the bombing is to be handed to police.
The report from the Historical Enquiries Team (HET) will be examined by serious crime branch detectives who will determine whether any fresh criminal proceedings can be taken against the perpetrators of the bombing.