The Garda Commissioner, Martin Callinan, has extended his condolences to the family and colleagues of the PSNI officer who was killed in Derry overnight.
The 27 year old female police officer was on routine patrol when the vehicle she was in collided with what is believed to be a stolen car on the Limavady Road.
Two other officers, who were in the car at the time, sustained minor injuries during the incident.
Two men were spotted fleeing the scene.
The North's Justice Minister, David Ford, says those involved need to come forward: