Police in Northern Ireland are investigating whether the New IRA was responsible for the attempted murder of two officers on patrol in Co Tyrone.
PSNI assistant chief constable Bobby Singleton said the location of the incident yesterday in Strabane and previous attacks made the involvement of the dissident republican splinter group a "strong line of inquiry".
Two officers escaped injury in the attack at Mount Carmel Heights after a bomb detonated at the side of their vehicle.
Police have said they have discovered what could be a command wire for the improvised explosive device during follow-up searches.
A major security alert is continuing in the area, affecting more than 1,000 residents and leaving some children unable to get to school.
Providing an update on the investigation, Mr Singleton said: "Shortly before 11pm last night two of the officers from the Strabane response local policing team were on duty in the Mount Carmel Heights area, they were conducting routine patrols in relation to ongoing antisocial behaviour in the area when they observed a flash and heard a loud bang.
"They left the area, came back to the station and they found evidence of some blast damage to their police vehicle.
"They later returned to the scene in a controlled fashion and established what they believe to have been the location of an explosion.
"We then moved into a security operation in the Mount Carmel Heights area.
"We have somewhere in the region of 1,000 residents who have been affected by that security alert.
"Our thoughts are first and foremost with the two police officers who were here last night serving their community.
"Fortunately they are left simply shaken by what happened last night, but we are treating this incident as a credible attempt to murder those officers."
He said: "We have seen evidence of what we believe is a viable explosive device.
"Fortunately the officers have not been injured in this attack but this attack took place in a busy residential area, it was absolutely reckless and any member of the public, never mind our police officers, could have been seriously injured."
Asked who could be responsible, the officer said: "Given the location of the attack and previous incidents, a strong line of inquiry would be the New IRA."
Mr Singleton said PSNI chief constable Simon Byrne had met local officers in Strabane to offer his support.
Sinn Fein vice president Michelle O'Neill said any attempt to kill officers was "reprehensible".
She tweeted: "Those involved in this attack will not succeed in dragging society backwards.
"We must all unite against these reckless actions. We must keep building the peace and moving forward."
Any attempt to attack or kill police officer's is reprehensible. Those involved in this attack will not succeed in dragging society backwards. We must all unite against these reckless actions. We must keep building the peace and moving forward.— Michelle O’Neill (@moneillsf) November 18, 2022
DUP leader Jeffrey Donaldson said: "This callous and seemingly pre-meditated attack must be roundly condemned.
"My thoughts first and foremost are with the officers affected, their loved ones and PSNI colleagues as they come to terms with has happened.
"Attempts on the life of police officers were wrong in the past and remain wrong today. There is always an alternative to violence.
"Northern Ireland will not be held to ransom by fringe elements intent only on bloodshed and dragging our society backwards.
"It is clear from the scenes this morning that those responsible for such cowardly acts offer nothing but hurt and disruption for the communities they purport to represent.
"Political leadership is needed to send a strong message that this behaviour has no place in our society."
Taoiseach Micheál Martin was in Newry, Co Down, when news of the attack began to emerge.
He said: "I have just been hearing news overnight and we do need further clarity in terms of what happened here and I understand an investigation is under way.
"But any such attempt to injure members of the security forces or the PSNI would be absolutely shocking and stands to be condemned.
"It is quite shocking, if that is the case, that something like that would happen."
The PFNI said the attack in Strabane was a "desperate, reckless act to murder officers working for the entire community".
PFNI chair Liam Kelly said: "The terrorist goal was to cause heartache and misery and return Northern Ireland to the dark ages.
"We are grateful that officers in the vehicle targeted by these cowards were unhurt.
"The attackers wanted their roadside device to cause maximum damage and we are thankful they failed in their objective.
"Nothing is gained by such a callous, hate-filled incident. The terrorist threat is rated 'substantial' and I would appeal to all officers to step up their vigilance.
"This attack is a reminder to us all that terrorists are still active in our community."
Sinn Féin leader Mary Lou McDonald said that "those who attack or threaten police officers will not drag us back".
"We are going forward. Solidarity to the PSNI officers targeted last night, to their families and colleagues," Ms McDonald posted on Twitter.
Those who attack or threaten police officers will not drag us back. We are going forward. Solidarity to the PSNI officers targeted last night, to their families and colleagues.— Mary Lou McDonald (@MaryLouMcDonald) November 18, 2022
Speaking on RTÉ's Drivetime, SDLP Councillor Jason Barr said the attack on two police officers in Strabane "needs to be condemned fully".
Mr Barr said there had been no other attacks this year and things "seemed to be pointing in the right direction".
"This has brought us way back to more or less square one again," he said.
"Those who are doing this have no place in this society at all … hopefully those that did this and disrupted the lives of many, many people will be caught and brought to justice, where they should be."
With additional reporting by PA