A teenager and a 37-year-old man have been arrested by detectives investigating the murder of a policeman in Northern Ireland.

Constable Stephen Carroll, 48, was shot in the back of the head when a gunman fired through the rear window of his unmarked patrol car.

Police said an 17-year-old boy and the man had been detained in Craigavon, Co Armagh, where the officer became the first member of the PSNI to be murdered.

Dissident republicans of the Continuity IRA have claimed responsibility.

Constable Carroll's devastated wife Kate said: "A good husband has been taken away from me and my life has been destroyed."

Constable Carroll was with two other tactical support group members providing cover, support and protection for two neighbourhood officers, when he was ambushed.

They were in a back-up car as two colleagues who had travelled separately spoke with a distressed woman after her window had been smashed.

Fearing it might be an attempt to draw them into a line of fire, they delayed their response for an hour before driving into the Lismore Manor housing development at Craigavon, Co Armagh.

The two investigating officers got out to visit the woman's house, while the other three waited.

A gunman then emerged out of the darkness and fired twice through the rear window of Constable Carroll's Skoda.

-Nova