A police officer is in a stable condition in hospital after he was shot by a dissident republican gunman on the Crumlin Road in north Belfast.
The officer was hit twice in the arm after a number of shots were fired from a car.
A 36-year-old man has been arrested in the Cliftonville Road area of north Belfast.
The incident happened close to a petrol station at about 7.30 pm.
Police have said their main line of inquiry is “violent dissident republicans”.
The Crumlin Road remains closed this morning, Monday, January 23.
Northern Ireland Secretary James Brokenshire and the NI Justice Minister Claire Sugden have described the attack as “sickening”.
Assistant Chief Constable Mark Hamilton said the attack was “reckless madness” and warned that there could have been “multiple deaths”.
“This was a very concerted attack on our officers – a very concerted attempt to murder them,” he added.
“Our main line of inquiry at the minute is violent dissident republicans. One arrest has already been made.”
Mr Brokenshire said in a tweet that he had spoken to the PSNI chief constable George Hamilton and had been briefed about the “active investigation”.
He added that his personal thoughts “were for the injured officer and appreciation of all PSNI officers who put themselves in harm’s way to keep us safe”.
The chief constable tweeted that “brave officers” had been “attacked by faceless people with gunfire”.
Mark Lindsay, chairman of the Police Federation for Northern Ireland, said it was “an appalling act”.
“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,” he said.
“They believe that by causing great grief to a family they are somehow advancing their warped and outdated plan. The wider community will be outraged by this attack on one of their police officers.
“The police serve the entire community and wounding one individual is an attack on the entire community.
“This attempted murder underlines the fragility of our peace.”