A 36-year-old man has been arrested after a policeman was shot in north Belfast, police said.
The community officer suffered at least two bullet wounds to the arm as he emerged from a petrol station on Sunday night.
He is stable in hospital, his injuries are not believed to be life-threatening and police hope he will make a full recovery.
There's been widespread condemnation of the attack, with warnings that a return to violence cannot, and will not, be tolerated.
Taoiseach Enda Kenny says it was an "outrageous and cowardly act" while the Tánaiste and Justice Minister Frances Fitzgerald says it was "despicable" and Fianna Fáil Leader Micheál Martin says its "appalling and deeply shocking".
A senior officer blamed violent dissident republicans.
Police Service of Northern Ireland (PSNI) assistant chief constable Mark Hamilton said: "This was a very concerted attack on our officers - a very concerted attempt to murder them."
He confirmed one arrest had been made in north Belfast but said others were involved in planning the pre-meditated attempt to kill on the Crumlin Road.
He appealed for anyone who saw an Audi vehicle at the scene to contact detectives.
Several shots were fired. The injured officer has been taken to the Royal Victoria Hospital in Belfast where he was undergoing surgery.
Mr Hamilton said he was conscious and was doing as well as could be expected.
"We are hopeful that he will make a full recovery but this is a deeply shocking event, something that will take him some time to recover from."
He confirmed detectives' main line of inquiry was violent dissident republicans.
Mr Hamilton added: "These were two community police officers going about community policing roles that this community needs them to do and they have been violently attacked in this community.
"I would utterly condemn this, this is the first shooting attack upon police for some time, it is the first one this year, it is totally unnecessary, appalling and needs to be utterly condemned by all sides of this community."
Police want to speak to anyone who saw an Audi-type vehicle opposite the filling station at around 7.30pm.
"This was not just an attack upon police, it was very clearly an attack upon the community.
"Other lives could easily have been lost.
"Reckless madness, and I can assure this community that every resource we have has been turned to find these people and bring them to justice."
Dissident republicans have attempted to kill several members of the security forces in Northern Ireland in recent years. Police, soldiers and prison officers have all died at their hands.
The attack comes amid warnings that a political vacuum has been created by the collapse of Stormont power-sharing.
Mark Lindsay, chairman of the Police Federation of Northern Ireland, said: "This attack on the life of an officer is a stark reminder of the determination on the part of terrorists to murder and maim police officers.
"They believe that by causing great grief to a family they are somehow advancing their warped and outdated plan."
He said it underlined the fragility of the peace.
The threat against police is classed as severe and Mr Lindsay warned officers to be vigilant.
The attack comes as Northern Ireland prepares for fresh elections after the collapse of power-sharing.
Former deputy first minister Martin McGuinness resigned in protest over a botched green energy scheme which is predicted to leave taxpayers millions out of pocket.
Democratic Unionist MP Nigel Dodds said it was a despicable act.
Northern Ireland Secretary James Brokenshire said he was "shocked and appalled" at the "cowardly shooting": "To attack officers who are going about their daily duty protecting the entire community is sickening."