Belfast police say a suspected car bomb has detonated in the city, injuring a prison officer.
"We can confirm that the man injured following the explosion of a device under his van is a serving prison officer," a police spokeswoman said.
Police said the condition of the man was not yet known.
A 1998 peace deal largely ended three decades of violence in Northern Ireland between Protestants who want to remain British and Catholics favouring unification with Ireland, but pockets of division and sporadic violence remain.
The splinter militant groups that carry out the attacks have targeted police and security forces in particular in recent years.
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The victim of the attack early on Friday was a 52-year-old prison officer, police said. He worked in a training school rather than in a prison, Finlay Spratt, head of the Prison Officers Association, told Reuters.
"This is just terrible. What can you say, we have been down this road before. These people have no justification for what they do," Spratt said.
Northern Ireland's leader Arlene Foster, whose father, a police officer, survived being shot in the head by the Irish Republican Army when she was eight, said on her official Twitter account that the attack was "disgraceful and despicable".
In 2012, a Northern Irish prison officer was killed in a motorway shooting blamed on militant nationalists - the first murder of a prison officer since 1993.
