Two teenagers have been arrested over the murder of a journalist in Northern Ireland, in the latest flare-up of violent protests.
Two teenagers have been arrested by police in connection with the murder of journalist Lyra McKee in Northern Ireland.
The men, aged 18 and 19, were detained under anti-terrorism legislation and have been taken to a police station in Belfast for questioning, the Police Service of Northern Ireland (PSNI) said.
An outpouring of tributes to the 29-year-old was led by her partner, Sara Canning, who said Ms McKee's "amazing potential was snuffed out by this single barbaric act".
Ms Canning said: "The senseless murder of Lyra McKee has left a family without a beloved daughter, a sister, an aunt, and a great aunt, has left so many friends without their confidant, victims in the LGBTQIA community are left without a tireless advocate and activist, and it has left me without the love of my life, the woman I was planning to grow old with."
"We are all poor for the loss of Lyra. Our hopes and dreams and all of her amazing potential was snuffed out by a single barbaric act," she said.
"This cannot stand. Lyra's death must not be in vain because her life was a shining light in everyone else's life, and her legacy will live on in the light that she has left behind."
Detectives hunting the gunman have released footage of the shooting in the hope the community can help trace her killers.
The published author, from Belfast, was shot in the head by suspects who police believe were dissident republicans linked to the New IRA, as they clashed with police on the Creggan estate in Londonderry on Thursday night.
Tributes flow for Lyra McKee
A journalist has been shot dead during riots in Northern Ireland in what police are treating as a terrorist incident, following the latest upsurge in violence to shake the troubled region.
"Lyra McKee was murdered during orchestrated violence in Creggan last night," Assistant Chief Constable Mark Hamilton said in a statement.
Ms McKee, 29, had earlier posted an image that appeared to be from the riots in the Creggan housing estate in the city of Londonderry, also known as Derry, accompanied by the words "Derry tonight. Absolute madness."
Police in Northern Ireland said the dissident republican group the New IRA was probably responsible for the fatal shooting.
Mr Hamilton said a gunman fired a number of shots at police during the unrest.
"We believe this to be a terrorist act. We believe it has been carried out by violent dissident republicans," he said.
Ms McKee was highly regarded by her friends and journalistic colleagues, who took to Twitter to mourn her death on Thursday night.
Ms McKee was based in Belfast and focused her work on the impact of violence in Northern Island.
On Twitter, her friends described her as an "exceptional journalist", their "mentor" and a "huge talent".
In 2016, she was named by Forbes as one of their European '30 under 30' in the media and she had recently signed a two-book deal with Faber, who described her as a "rising star of investigative journalism".
Images of the unrest posted on social media showed a car and van ablaze and hooded individuals throwing petrol bombs and fireworks at police vehicles.
"A single gunman fired shots in a residential area of the city and as a result wounded Ms McKee," Hamilton said.
"We are treating this as a terrorist incident and we have launched a murder enquiry."
Journalist Matthew Hughes earlier identified the dead woman as one of his friends.
"I just received the heartbreaking news that my friend @LyraMcKee was murdered tonight in a terrorist incident in Derry," he wrote on Twitter.
Leona O'Neill, a reporter with the Belfast Telegraph, said she had been next to the woman when she was shot.
"I was standing beside this young woman when she fell beside a police Land Rover tonight in Creggan #Derry. 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," she tweeted.
Good Friday Agreement
The violence came in the run-up to the Easter weekend when Republicans opposed to British presence in Northern Ireland mark the anniversary of a 1916 uprising against British rule.
A car-bombing and the hijacking of two vans in Derry earlier this year were also blamed on a dissident paramilitary group.
Michelle O'Neill, the deputy leader of Irish republican party Sinn Fein, condemned those responsible for the killing.
"My heart goes out to the family of the young woman shot dead by so-called dissidents," she said.
"This was an attack on the community, an attack on the peace process and an attack on the Good Friday Agreement," the peace deal that largely brought an end to violence on the island exactly 21 years ago, she added, calling for calm.
Arlene Foster, leader of the Democratic Union Party, which is in favour of Britain's presence in Northern Ireland, described the death as "heartbreaking news".
"A senseless act. A family has been torn apart. Those who brought guns onto our streets in the 70s, 80s & 90s were wrong. It is equally wrong in 2019. No one wants to go back," she wrote on Twitter.
The Good Friday Agreement in 1998 largely brought an end to three decades of sectarian bloodshed in Northern Ireland between republican and unionist paramilitaries, as well as British armed forces, in a period known as "the Troubles".
Some 3,500 people were killed in the conflict - many at the hands of the Irish Republican Army (IRA).
Police have blamed a group called the New IRA for the flare-up in violence in recent months.
Some have expressed fears that recent attacks could be a sign that paramilitaries are seeking to exploit the current political turbulence over Northern Ireland and its border with the Republic of Ireland caused by Brexit.
Derry was the scene of one of the darkest episodes in the Troubles in 1972, known as Bloody Sunday, when British troops opened fire on a civil rights demonstration and killed 13 people. A 14th victim later died of his wounds.
A photograph of a Catholic priest waving a bloodstained handkerchief as he tried to help 17-year-old victim Jackie Duddy to safety became a defining image of the incident.
Following a long-running public inquiry in 2010, Britain's then-prime minister David Cameron issued a formal state apology for the killings, calling them "unjustified and unjustifiable".
A former British soldier was charged with murder last month over the killings.
The ex-paratrooper, identified only as Soldier F, is accused of murdering two people and the attempted murder of four others in what was an early turning point in the history of the Troubles.