Stormont leaders have stood shoulder-to-shoulder with PSNI Chief Constable Simon Byrne after the shooting of a senior detective.
Detective Chief Inspector John Caldwell remains critically ill in hospital and heavily sedated after the attack at a sports centre in Omagh on Wednesday.
Four men have been arrested in Co Tyrone in the attempted murder investigation.
The chief constable said he had spoken to Mr Caldwell’s wife and son, who he said have been heavily affected by the incident, and they want to pass on their thanks both to first aiders at the scene, and for the outpouring of support across the community.
Sinn Fein vice-president Michelle O’Neill, DUP leader Sir Jeffrey Donaldson, Alliance deputy leader Stephen Farry, UUP leader Doug Beattie and SDLP leader Colum Eastwood met with Mr Byrne at police headquarters in Belfast on Friday morning.
They then took part in a joint press conference with Mr Byrne, who hailed the importance of the act of political unity.
“We echo our thanks because it has rippled through the organisation about how important it is that we’re joined by the political leaders today at this unique time to show that we stand together and call out this outrage for what it is,” Mr Byrne said.
Ms O’Neill has emphasised the importance of unity in the wake of the attack.
“We do stand here united as one voice in our condemnation against this horrific attack on a police officer, someone who is part of our community,” she said.
“I think that the most powerful message that we, as political leaders (can do, is) to stand with the chief constable today, to stand with the police service and say, this is not good enough.
“This is an attack on all of us, this is an attack on our community.”
Sir Jeffrey warned: “I would say to the evil people who carried out this heinous attack and to their organisation – you are not the future of this place. We stand against you.
“The murder of police officers and the attempted killing of those who serve our communities in Northern Ireland is unacceptable.
“My cousin was the first RUC officer to be murdered by the IRA in 1970. Loyalists have also killed police officers. It was never acceptable and it is not acceptable now.
“It will not be tolerated and we stand foursquare with the police to ensure that those who have been responsible for this attack are brought to justice and that they do not dictate how this place moves forward in the future.”
Gunmen shot Mr Caldwell in front of his young son while the detective was coaching a sports team at the Youth Sports Centre on Wednesday evening.
Mr Caldwell ran a short distance and fell to the ground, where the attackers continued to fire at him as children ran in terror to get to safety, police said.
A 22-year-old was arrested in the Coalisland area on Friday morning.
Three men aged 38, 45 and 47 also arrested in Co Tyrone remain in custody.
The dissident republican group the New IRA are the “primary focus” of the probe, police have said.
On Thursday, Mr Byrne said the PSNI as an organisation, are “utterly shocked and angered by last night’s brazen and calculated attack”.
He added: “John is a father, husband and colleague, and a valued and active member of his local community.”
He said Mr Caldwell has been a police officer for 26 years and is “committed to public service as a senior investigating officer supporting victims and their families in bringing offenders to justice”.
Mr Byrne said: “This has sent a huge shockwave across the organisation.
“We’ve been speaking principally with the Police Federation but also with those representatives of senior officers and police staff who would see themselves under threat.
“Clearly, one of the things that defines us is our resilience and our commitment to keep going in dark times and tough times.
“So John knows that his colleagues will now be working tirelessly around the clock to support his recovery, but also to bring the offenders that have tried to kill him to swift justice.”
Assistant Chief Constable Mark McEwan said there were “many other young people, children” waiting to be picked up by their parents when the attack on Mr Caldwell took place.
“Those children ran for cover in sheer terror,” he told reporters.
“The two gunmen, who were dressed in dark clothing, carried out this cowardly attack and left the scene on foot. At least two other vehicles were struck by their volley of shots.
“We believe the gunmen fled the scene in a small, dark-coloured vehicle shortly after 8pm. We believe this vehicle was abandoned and set on fire in Racolpa Road, Omagh.
“We want to hear from anyone who was in the area or who witnessed what happened to get in touch with any information that could help with our investigation.”
Mr Caldwell has led a number of major investigations, including taking a key role in the murder probe following the killing of Natalie McNally in Lurgan in December.
Irish police are working closely in co-operation with their counterparts in the PSNI and have intensified patrols.
The New IRA has been blamed for the killing of journalist Lyra McKee in Londonderry in 2019.
Last November, the group was also thought to be behind the attempted murder of two police officers in a bomb attack in Strabane, Co Tyrone.
Omagh has seen significant dissident violence in the past, including a Real IRA bomb attack in 1998 which killed 29 people – one of whom was a woman pregnant with twins.
It was also where Constable Ronan Kerr was murdered in April 2011.
The terrorism threat level in Northern Ireland was lowered from severe to substantial for the first time in 12 years last March.
