• Assistant Chief Constable Mark Hamilton said the New IRA "are likely to be the ones behind this"
• Prime Minister Theresa May said the murder was "shocking and senseless"
A journalist ha been shot dead during rioting in Londonderry, North Ireland, that police are treating as a "terrorist incident".
Dissident republicans are being blamed for killing 29-year-old Lyra McKee during rioting after police searches in Derry's Creggan area on Thursday night.
Assistant Chief Constable Mark Hamilton said the New IRA "are likely to be the ones behind this" and detectives have started a murder inquiry.
Prime Minister Theresa May said the murder was "shocking and senseless".
McKee was a journalist who "died doing her job with great courage", added Mrs May.
The Police Service of Northern Ireland said that a gunman fired shots towards police at about 9pm on Thursday.
Mobile phone footage taken by a bystander during Thursday night's rioting appears to show a masked gunman crouching down on the street and opening fire with a handgun.
Ms McKee, who was standing near a police 4x4 vehicle, was wounded.
"She was taken away from the scene in a police Land Rover to Altnagelvin Hospital but unfortunately she has died," said Hamilton.
The National Union of Journalists (NUJ) said Ms McKee was "one of the most promising journalists" in Northern Ireland.
She was a journalist of "courage, style and integrity" and a "woman of great commitment and passion", said the union's Séamus Dooley.
"I have no doubt that it was that commitment which led to her presence on the streets of the Creggan last night, observing a riot situation in the city."
The Irish Prime Minister Leo Varadkar said: "Our solidarity also goes out to the people of Derry and to the entire journalism community.
"We cannot allow those who want to propagate violence, fear and hate to drag us back to the past."
The violence broke out after police raids on houses in the Mulroy Park and Galliagh areas in Derry.
"Violent dissident republicans are planning attacks in this city and we were carrying out a search operation in Creggan," said Mr Hamilton.
Rioting began at Fanad Drive in the city and more than 50 petrol bombs were thrown at police and two vehicles hijacked and set on fire.
"I believe that this was orchestrated - orchestrated to a point that they just want to have violence and attack police," said Mr Hamilton.
"Bringing a firearm out is a calculated and callous act."
One reporter who was at the scene said a gunman "came round the corner and fired shots indiscriminately towards police vehicles".
"There were a number of houses with families - they had all spilled out on the street to see what was happening," added Leona O'Neill.
"There were young people, there were children on the street, there were teenagers milling about and a gunman just fired indiscriminately up the street."
Northern Ireland Secretary Karen Bradley said the "intolerable actions" of those behind Ms McKee's murder were "rejected by the overwhelming majority of people who want to build a peaceful and more prosperous future for everyone in Northern Ireland".
Archbishop Eamon Martin, the head of the Catholic Church in Ireland, tweeted to ask people to pray for Ms McKee's family.
Sinn Féin's vice-president Michelle O'Neill said she was "shocked and saddened at the tragic news", adding: "I unreservedly condemn those responsible for killing this young woman."
Democratic Unionist Party (DUP) leader Arlene Foster tweeted: "Heartbreaking news. A senseless act. A family has been torn apart."