Police in Northern Ireland have confirmed dissident republican group the New IRA is now their primary line of inquiry following the shooting of an off-duty officer.

Detective Chief Inspector John Caldwell remains critically ill in hospital and heavily sedated after the attack at a sports centre in Omagh on Wednesday.

Police confirmed on Friday evening that they had made a fifth arrest in connection with the attempted murder.

Chief Constable Simon Byrne 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.

Assistant Chief Constable Mark McEwan confirmed they are treating the attack as terrorist-related.

“Our primary line of inquiry is the New IRA,” he said.

“Detectives want anyone who was in the area or who witnessed what happened to call 101 quoting reference number 1831 of 22/02/23.”

Police also confirmed that a 43-year-old man had been arrested in the Stewartstown area on Friday and was being questioned by detectives in Musgrave serious crime suite.

Four other men, aged 22, 38, 45 and 47, previously arrested in connection with the attempted murder remain in police custody.

Earlier Stormont’s political leaders met with Mr Byrne.

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 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.

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.

On Thursday, Mr Byrne said the PSNI as an organisation was “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.”

Mr 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.