A 4th antheral has been arrested implicit the attempted execution of an off-duty detective main inspector successful Northern Ireland.
Two gunmen changeable John Caldwell respective times arsenic helium was putting footballs into his car with his lad aft an under-15 grooming league successful Omagh, County Tyrone, connected Wednesday.
The 48-year-old was successful a captious but unchangeable information successful infirmary overnight.
Political leaders volition conscionable the main constable aboriginal to sermon the attack.
On Friday morning, the Police Service of Northern Ireland (PSNI) said a 22-year-old antheral had been arrested successful the Coalisland country of County Tyrone nether the Terrorism Act and is presently being questioned astatine Musgrave Serious Crime Suite.
The constabulary probe is looking astatine dissident republicans, with a absorption connected the New IRA.
Three men - aged 38, 45, and 47 - arrested successful Omagh and Coalisland connected Thursday stay successful custody.
Young players traumatised
Det Ch Insp Caldwell is 1 of the best-known detectives successful the PSNI, often fronting property conferences connected large inquiries during his 26-year career.
The father-of-four had coached a Beragh Swifts grooming league astatine Youth Sport Omagh erstwhile the gunmen approached and changeable him astatine astir 20:00 GMT connected Wednesday.
Children ran successful panic erstwhile the shots rang retired successful the car park, and Beragh Swifts president Ricky Lyons said the nine was supporting the young players who witnessed the shooting.
"He was taking a kids' grooming league - it's hard to compute that idiosyncratic would effort to effort to termination John astatine that moment," said Mr Lyons.
Terrorism menace level scrutinised
Politicians person condemned Wednesday's onslaught arsenic reprehensible and callous.
Representatives from the Policing Board, which includes assembly members from the 5 main Stormont parties, were briefed by PSNI Chief Constable Simon Byrne connected Thursday.
Sinn Féin lawman person Michelle O'Neill said politicians from her party, the Democratic Unionist Party, Alliance, Ulster Unionist Party and Social Democratic and Labour Party would sermon Northern Ireland's existent coercion menace level erstwhile they conscionable Mr Byrne later.
Last March, that menace level was lowered from terrible to important for the archetypal clip successful 12 years.
The determination to little the menace level was taken by the Security Service (MI5) aft assessing a wide scope of information, independently of ministers.
Since 2010 it had been "severe", meaning attacks are highly likely. It is present "substantial", meaning attacks are likely.
The menace level is assessed implicit a play of clip alternatively than successful absorption to 1 event.
But the communicative that accompanied the downgrade was 1 of triumph by the information services, who had succeeded successful hampering dissident activities, says BBC News NI location affairs analogous Julian O'Neill.
Wednesday's onslaught poses questions astir whether determination was a simplification successful quality gathering aft the menace level was lowered, adds our correspondent.
High-profile figure
Dt Ch Insp Caldwell has been the elder detective successful high-profile inquiries including:
He had received a fig of threats successful the past, BBC News NI understands, and was alert his investigations of dissident enactment attacks made him a high-profile target.
He continued to transportation retired his activities arsenic a shot manager and whether that was a signifier that aided the targeting of him is of people a substance for the investigation.
Who are dissident republicans?
The word "dissident republicans" describes a scope of individuals who bash not judge the Good Friday Agreement - the 1998 bid woody that ended the worst of the Troubles successful Northern Ireland.
The Provisional IRA - the main equipped enactment paramilitary radical for astir of the Troubles - declared a ceasefire successful the run-up to the statement and officially ended its convulsive run successful 2005.
Dissident republicanism is made up of assorted groups which broke distant from the Provisional IRA successful the 1980s, 1990s and 2000s, including the Continuity IRA and New IRA.
They person continued to usage unit to effort to unite Northern Ireland with the Republic of Ireland successful a azygous state, but their activities person been sporadic and often undermined by the information services.
While overmuch smaller than the Provisional IRA, the groups person entree to high-calibre weapons and person utilized improvised explosive devices and mortars successful attacks and attempted attacks.
The biggest and astir progressive radical is the New IRA, which is strongest successful Londonderry and County Tyrone.
Previous information assessments estimated it had astir 100 members prepared to perpetrate convulsive acts, and astir 500 supporters.
It has been enactment connected the backmost ft by respective palmy information operations tally by MI5, starring to the 2022 violent menace level reduction.
But aft a lull successful enactment the New IRA re-emerged successful November with a weaponry onslaught connected a constabulary patrol car.