A PSNI officer has been killed after a device exploded under a car in the Highfield Close area of Omagh, Co Tyrone.
Ronan Kerr, 25, was killed when a device exploded under his Ford Mondeo car outside his home just before 4pm today as he left for work.
The victim is understood to have recently graduated from the PSNI training college.
He was in the car alone when neighbours rushed to the scene seconds after the bomb exploded.
About 2,000 people taking part in the Omagh Half Marathon passed the entrance to the estate just hours before the blast.
The area has been sealed off and the PSNI is investigating.
Taoiseach Enda Kenny said: 'I utterly condemn today's horrific bomb attack in Co Tyrone. This was a heinous and pointless act of terror.
'Those who carried it out want to drag us back to the misery and pain of the past.
'They are acting in defiance of the Irish people. They must know that they can never succeed in defeating the democratic will of the people. '
Northern Ireland's First Minister Peter Robinson has said it was an evil act by a miniscule group that wanted to 'drag us back into the past' but that the community would unite against such violent threats.
Mr Robinson has appealed to people with information to come forward so that those behind the attack could be brought to justice.
British Prime Minister David Cameron has condemned the 'wicked and cowardly' bomb attack and said that the perpetrators were trying to take Northern Ireland back to a 'dark and bloody past', and the authorities would 'not rest' until they were caught.
Tánaiste Eamon Gilmore has condemned the actions of those responsible for the attack. He said that 'those behind such violence have no mandate and are acting contrary to the democratic will of the people of Ireland, north and south.'
Minister for Justice Alan Shatter has described the killing as 'disgraceful' and said the revulsion felt among gardaí would reinforce the determination to do everything possible to counteract the threats posed by dissident groups.
Sinn Féin President Gerry Adams said 'Sinn Féin is determined that those responsible will not set back the progress of the Peace and Political Process.'
Reaction from religious leaders
Archbishop of Armagh and Primate of All Ireland Cardinal Seán Brady has said that 'the deliberate taking of innocent human life is always wrong'.
Cardinal Brady said: 'I implore the perpetrators of this shameful killing to realise the futility of their actions, and to call off this senseless campaign.'
Presbyterian Moderator Dr Norman Hamilton has said 'the courage and commitment of the PSNI officer who has given his life are the qualities we all must show, as we continue to build our shared future together and banish hatred and killing to the past.'
Reverend Alan Harper, Archbishop of Armagh and Reverend Ken Good, Bishop of Derry and Raphoehave said 'we are resolved as Christian people to come together with all our neighbours in this community, regardless of politics or background.'
They continued 'we are building a community where hatred has no place and in which political difference will never be successfully addressed with violence.'