Police are looking for two men that left the scene where a 27-year-old officer died in a road crash involving a suspected stolen vehicle.
The officer was travelling in a police car on routine patrol when the incident happened in Londonderry last night.
Two other officers in the patrol car sustained non-serious injuries.
Police have appealed for witnesses to come forward.
More top news
Twenty-one-year-old pair raise nearly £40,000 in the world's toughest row.
An 11-year-old boy has been found guilty of shooting dead an eight-year-old girl in a row over a puppy.
A picture of a mother and her two daughters posted on social media has left people wondering "who's the mum?".