Continuity IRA shot dead officer
Dissident republicans, the Continuity IRA, have claimed they murdered a policeman in Northern Ireland.
He was Constable Stephen Paul Carroll, 48, a married man with children from the Banbridge area of County Down.
He died just 48 hours after two soldiers were shot dead by the Real IRA at an army base in Antrim.
Monday night's shooting happened at Lismore Manor, in Craigavon, County Armagh, after police responded to a call from a woman for help.
Constable Carroll was shot as he got out of a police car at about 2145 GMT. He died later from his injuries.
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.
There is believed to be cross-over and co-operation between the Continuity IRA and the larger Real IRA, which bombed Omagh in 1998 killing 29 people and injuring hundreds more.
Chief Constable Sir Hugh Orde called it a "sad day" for Northern Ireland's force and said the gunmen were "criminal psychopaths", but said he would not ask for the Army to help patrol NI's streets.
"I have no intention to ask the Army for routine military support, it's not necessary and it doesn't work," he said.
Sir Hugh held a joint press conference with the first and deputy first ministers Peter Robinson and Martin McGuinness at Stormont.
Mr Robinson said: "This is a battle of wills between the political class and the evil gunmen - the political class will win."
Mr McGuinness said the dissidents' actions were futile: "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."
Prime Minister Gordon Brown has condemned the murderers and insisted there would be "no return to the old days" in Northern Ireland.
"These are murderers who are trying to distort, disrupt and destroy a political process that is working for the people of Northern Ireland," he said.
Mr Brown, who travelled to Northern Ireland on Monday to visit the scene of the two soldiers' murders in Antrim, said gunmen would "never be allowed to undermine the political process".
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.
Constable Carroll was the first PSNI officer to have been murdered by paramilitaries since the force was formed in 2001.
Dissident republicans tried to kill two PSNI officers in shootings in Derry and Dungannon in November 2007.
They have also been linked to a booby trap bomb which exploded under a police officer's car in Spamount, County Tyrone in May 2008.
Politicians from all parties condemned Monday's killing, which Northern Ireland Secretary Shaun Woodward insisted would not damage the peace process.
Asked if the killing was linked to the soldiers' shooting at the weekend, Sir Hugh Orde said: "I think you are giving (the attackers) credit they ill deserve.
"I think these are disparate groups, badly infiltrated and indeed many awaiting trial north and south of the border.
"It just reminds us that a small group of people determined to wreck what is huge political progress are becoming more dangerous."
The first and deputy first ministers have again postponed an investment visit to the US following the murder.
In the weekend attack, Sappers Mark Quinsey, 23, from Birmingham and Patrick Azimkar, 21, from London, were shot dead at Massereene Army base, Antrim.
The soldiers were killed as they accepted a pizza delivery at about 2120 GMT on Saturday.
Four other people, including two pizza delivery men - Anthony Watson, 19, from Antrim, and a Polish man in his 30s - were injured in the attack. 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. How the barracks attack unfolded THE BBC.CO.UK