Lyra McKee murder was 'part of an orchestrated plot'
More than one person was involved in an orchestrated murder plot which left a young journalist dead, police said.
Lyra McKee, 29, was shot in the head during disturbances in Londonderry on Thursday evening.
Police blamed the New IRA and said the intention was to kill officers.
Deputy chief constable of the Police Service of Northern Ireland (PSNI) Stephen Martin said the hearts of people in the city were breaking.
He added: "They have been grossly disappointed with the image of their city across the world today."
He defended the decision to launch an operation earlier on Thursday aimed at thwarting dissident plans for "imminent" violence.
Violence broke out soon afterwards.
The senior officer said: "Police were in that estate last night carrying out lawful activity, trying to prevent future imminent violence.
"The full and total responsibility for Lyra McKee's death lies with the organisation that sent someone out with a gun."
He said he has viewed intelligence and convinced himself of the urgency and need for the operation.