Constable Stephen Paul Carroll, 48, was from Banbridge
Two men, aged 17 and 37, have been arrested in connection with the murder of a policeman in Northern Ireland.
Dissident republican group, the Continuity IRA, said it shot Constable Stephen Paul Carroll at Lismore Manor, Craigavon, County Armagh on Monday.
He was shot two days after the Real IRA murdered two soldiers in Antrim.
Meanwhile, there have been minor disturbances in Craigavon and wheeled bins set on fire after police raided homes near the scene of the killing.
Police said they were monitoring the situation and advised drivers to avoid the Ardowen area of Craigavon.
Constable Carroll, 48, a married man, with children from Banbridge, County Down, died when police were attacked as they responded to a woman's call for help.
Constable Carroll was shot through the rear window of his police car when he arrived at the scene at about 2145 GMT on Monday.
Police said they were looking for a man in a light-coloured top who was seen running from the area after the shooting.
At least two houses have been searched in the nearby Drumbeg estate.
There have been minor disturbances in the area
At a press conference on Tuesday afternoon, Chief Superintendent Alan Todd said the constable had given 23 years of service to the community, working with the police service.
The Continuity IRA is one of a number of dissident republican paramilitary groups opposed to the peace process which have carried out bomb and gun attacks on civilians and the security forces.
This is the first murder of a police officer in NI since 1998. Constable Frank O'Reilly was killed by a loyalist blast bomb during disturbances linked to the Drumcree dispute in 1998.
The last police officers murdered by republicans, RUC constables Roland John Graham and David Andrew Johnston, were shot dead by the IRA in Lurgan, County Armagh in June 1997.
Police chiefs from Northern Ireland and the Republic of Ireland are to meet on Thursday to assess the latest security threat posed by dissident republicans.
Chief Constable Sir Hugh Orde and Garda Siochána Commissoner Fachtna Murphy will meet in Belfast.
Both police forces are intensifying their efforts to penetrate dissident Republican groups.
Irish Justice minister, Dermot Ahern, said everything would be done to safeguard lives and peace.
"The people who perpetrated these awful atrocities are enemies of the Irish people, they're enemies of the peace process; they will not derail that peace process," he said.
Politicians from all parties condemned Monday's killing.
Speaking at Hillsborough Castle in County Down, the Northern Ireland Secretary, Shaun Woodward, said the peace process had "become unstoppable".
"Whatever way you look at this, these cowards, these criminals - they may have the power to take the life of a police officer or of two unarmed soldiers on Saturday evening - but they do not have the power to stop the peace process, they do not have the power to stop this political progress," he said.
Sinn Fein Deputy First Minister Martin McGuinness issued a strongly-worded condemnation of the two attacks.
"These people are traitors to the island of Ireland, they have betrayed the political desires, hopes and aspirations of all of the people who live on this island," he said.
"They don't deserve to be supported by anyone."
In the weekend attack, sappers Mark Quinsey, 23, from Birmingham and Patrick Azimkar, 21, from London, were shot at Massereene Army base, Antrim.
The soldiers were killed as they accepted a pizza delivery at about 2120 GMT on Saturday.
NORTHERN IRELAND SHOOTINGS
1. Sat 7 Mar, 2120 GMT: Sappers Mark Quinsey and Patrick Azimkar are killed outside the Massereene Army base, Antrim. Four other people, including two pizza delivery men, are injured. Dissident republican group Real IRA claims responsibility.
2. Mon 9 Mar, 2145 GMT: Police Constable Stephen Carroll is shot dead in Craigavon after responding to a call for help from a distressed woman. Splinter group the Continuity IRA says it was responsible.
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