A burning car in Creggan, Londonderry, after petrol bombs were thrown at police during riots (Picture: PA).
Dissident republican group the 'New IRA' has admitted responsibility for the murder of journalist Lyra McKee in Londonderry, offering “full and sincere apologies” to her family and friends.
Miss McKee was shot dead during unrest in the Creggan area of Derry on Thursday night.
In a statement given to The Irish News using a recognised code word, the New IRA offered ‘full and sincere apologies to the partner, family and friends of Lyra McKee for her death’.
The New IRA is the biggest of the dissident republican groups operating in Northern Ireland.
Police have said that they are treating it as a "terrorist incident" and that the intention was to kill officers.
On Tuesday, a 57-year-old woman was arrested under the Terrorism Act in connection with the murder.
Two teenagers aged 18 and 19 were also arrested on Saturday and taken to a police station in Belfast for questioning. They were later released without charge.
Police Service of Northern Ireland (PSNI) officers were carrying out a search operation in the Creggan area of Derry, aimed at disrupting dissident republicans ahead of this weekend's commemoration of the 1916 Dublin uprising that led to Irish independence.
Prime Minister Theresa May called the death of Ms McKee "shocking and truly senseless".
She said: "My deepest condolences go to her family, friends and colleagues.
"She was a journalist who died doing her job with great courage."
More than 50 petrol bombs were thrown at police officers and two cars were hijacked and set on fire.
During the unrest, a gunman fired a number of shots at police, Assistant Chief Constable Mark Hamilton said.
He added: "The bringing of a firearm out and firing it down a street in a residential area where they knew lots of people were standing about is a calculated and callous act and can only be designed to hurt and kill people.
"Bullets stop somewhere, and on this occasion they stopped fatally."
It is understood Ms McKee had recently moved to Derry to live with her partner.
She worked as an editor for California-based news site Mediagazer, a trade publication covering the media industry.
In 2016, Forbes Magazine named her one of their 30 under 30 in media. She had been working on a new book which had been due to be published in 2020.
Michelle Stanistreet, National Union of Journalists (NUJ) general secretary, said Ms McKee was one of the most promising journalists in Northern Ireland.
"A young, vibrant life has been destroyed in a senseless act of violence," Ms Stanistreet said.
"A bright light has been quenched and that plunges all of us in to darkness."
ACC Hamilton confirmed Ms McKee was wounded and taken away in a police Land Rover to Altnagelvin Hospital but died there.
He said she was a "perfectly innocent" bystander with a legitimate reason for being there but had not been "actively working" as a journalist that evening.
ACC Hamilton said: "We have now launched a murder inquiry here in the city.
"We believe this to be a terrorist act, we believe it has been carried out by violent dissident republicans, our assessment at this time is that the New IRA are most likely to be the ones behind this and that forms our primary line of inquiry.
"This is a horrendous act, it is unnecessary, it is uncalled for, it is totally unjustified."
One reporter, who was at the scene, said she stood beside Ms McKee as she fell and called the ambulance for her.
She tweeted: "I called an ambulance for her but police put her in the back of their vehicle and rushed her to hospital where she died. Just 29 years old. Sick to my stomach tonight."
Northern Ireland Secretary Karen Bradley said she was "deeply shocked and saddened" to hear of the death.
"My thoughts and condolences are with her family at this time," Ms Bradley added.
"Those responsible for last night's violence have nothing to offer anyone in Northern Ireland.
"Their intolerable actions are rejected by the overwhelming majority of people who want to build a peaceful and more prosperous future for everyone in Northern Ireland."
The New IRA has been linked with four murders, including Pc Ronan Kerr, who was killed by an under-car bomb in Omagh in 2011.
The group is also linked to the deaths of prison officers David Black, who was shot as he drove to work at Maghaberry Prison in 2012, and Adrian Ismay, who died in 2016 after a bomb exploded under his van outside his home in east Belfast.
The group is believed to have been formed between 2011 and 2012 following the merger of a number of smaller units, including the Real IRA - the group behind the 1998 Omagh bomb.
It is strongest in Londonderry, north and west Belfast, Strabane and other pockets in Co Tyrone, and Lurgan in Co Armagh.