The killing of journalist Lyra McKee has led to a « palpable change » in community sentiment in support of policing, a senior detective has said.
Ms McKee, 29, was shot while observing rioting in Londonderry’s Creggan estate in Northern Ireland on Thursday night.
Two teenage men, aged 18 and 19, have been arrested and are being held under the Terrorism Act.
On Saturday, Det Supt Jason Murphy, who is leading the investigation, urged people to come forward.
He said there was a sense that what had happened to Ms McKee had marked a « real sea change ».
Det Supt Murphy also warned that he had a broader concern about a « new breed of terrorist coming through the ranks ».
« And that is very worrying for me, » he added.
« Yesterday, my officers were on the ground and we identified a palpable change in community sentiment, particularly the community sentiment towards policing, » he added.
« Yesterday we realised that the vast majority of communities across the whole of Northern Ireland support policing and support police and they support the peace process.
« What we saw yesterday was the visible demonstration of that within the Creggan community. A community that has been very frightened for a long time and for a large part has been held to ransom by terrorist organisations that claims to represent them. »
Ms McKee was standing near a police 4×4 vehicle with other journalists when she was shot on Thursday night.
CCTV captured her final moments in the crowd and mobile phone footage showed the suspected gunman.
In the video, the masked attacker leans from behind cover and appears to fire shots towards police and onlookers.
The Police Service of Northern Ireland (PSNI) said a gunman fired shots towards police officers at about 23:00 BST on Thursday.
In a Facebook post, political party Saoradh – a group which police say are closely aligned to the New IRA – sought to justify violence on the night.
They said Ms McKee was killed « accidentally » by a « volunteer » after the PSNI raided houses in Derry.
Who are the New IRA?
The New IRA was formed in 2012 after a number of dissident republican organisations said they were unifying under one leadership and is believed to be the largest dissident republican organisation.
Saoradh, which means liberation in Irish, is a political group and has the support of prisoners from the dissident group referred to as the New IRA in Maghaberry and Portlaoise prisons.
It was founded in 2016.
According to its constitution, Saoradh’s objective is to « effect an end to Britain’s illegal occupation of the six counties » and establish a 32-county Irish Socialist Republic.
The party has been highly critical of Sinn Féin in the past, with its chairman describing members as « false prophets who have been defeated and consumed by the very system they claim to oppose ».
There has been widespread condemnation of the killing.
At a vigil in Derry on Friday, Ms McKee’s partner, Sara Canning, described her as a « tireless advocate and activist » for the LGBT community.
Ms Canning said her partner’s dreams had been « snuffed out by a single barbaric act » and she had been left without « the woman I was planning to grow old with ».
« The senseless murder of Lyra McKee has left a family without a beloved daughter, a sister, an aunt and a great-aunt; so many friends without their confidante, » added Ms Canning.
« We are all poorer for the loss of Lyra. »
Secretary of State Karen Bradley made a private visit to Londonderry to sign the book of condolence for Ms McKee.
Ms McKee’s killing came 21 years after the Good Friday peace agreement was signed in Northern Ireland.
The 1998 peace deal marked the end in the region of decades of violent conflict – known as the Troubles – involving republicans and loyalists during which about 3,600 people are estimated to have died.
The Good Friday Agreement was the result of intense negotiations involving the UK and Irish governments and Northern Ireland’s political parties.
Figures from across the political divide, including Sinn Féin leader Mary Lou McDonald and DUP leader Arlene Foster, were among the hundreds of people to attend the vigil.
One of Ms McKee’s close friends, Kathleen Bradley, told the BBC: « Lyra was a voice – she wasn’t afraid to stand up and hold her view.
« Lyra managed to get Mary Lou McDonald and Arlene Foster into Creggan [for the vigil] without any high security or barricades.
‘Power of Lyra’
« Those politicians stood amongst us today and that really is the power of Lyra. »
Other leading world figures united to condemn Ms McKee’s killing.
Taoiseach (Irish Prime Minister) Leo Varadkar said Ms McKee « changed lives » as a journalist and an activist and would continue to do so.
« We stand with you as strong as your walls and for as long as they stand, » he added.
« This was an attack not just on one citizen – it was an attack on all of us, our nation and our freedoms. »
Former US President Bill Clinton said he was « heartbroken ».
Irish President Michael D Higgins signed a condolence book at Belfast City Hall and said there was « outrage » in Ireland.
« The loss of a journalist at any time in any part of the world is an attack on truth itself, » he said.
« The circumstances in which it happened – the firing on a police force that are seeking to defend the peace process – cannot be condoned by anybody. »
The EU’s chief Brexit negotiator, Michel Barnier, tweeted that Ms McKee’s killing was a « reminder of how fragile peace still is in Northern Ireland ».
« We must all work to preserve the achievements of the Good Friday Agreement, » he said.