Two suspects have been arrested in connection with the shooting of a police officer in Dungannon, Co Tyrone, on Monday.
The arrests took place early yesterday and the PSNI would only say that a man and a woman had been detained and were helping police with their inquiries into the attempted murder of the off-duty officer.
His condition in Craigavon Area Hospital in Co Armagh is said to be stable despite being seriously injured.
Chief Constable Sir Hugh Orde, reacting to the second shooting of a PSNI officer within five days, said yesterday: "This will not deter police officers going about their day to day duties of protecting communities in Northern Ireland."
". . .If a small number of disenfranchised people who have been rejected by their communities wish to continue this, we will pursue them to the ends of the earth if we need to."
Sir Hugh met senior figures in the DUP at Stormont yesterday in connection with the attacks on the PSNI and with the murder of Paul Quinn from Cullyhanna.
Police Federation spokesman Terry Spence, who heads the police officers' association, said: "Those people who were previously involved in the Provisional IRA are best placed to give information to the police about who these individuals are.
"They know who these dissident republicans are, and if they are signed up to the peace process, it's up to them also to do something about it and come forward to the police."
Sinn Féin president Gerry Adams has denounced the shooting of police officers and said those responsible had no mandate to target the police service and claimed that all such actions should stop.
The West Belfast MP said his offer to hold talks with dissident republicans, aimed at ending such attacks, remained open.
"I am still prepared to meet them. They have so far declined that offer," he said.
"What I want to do is persuade them that republican objectives are not served by these actions. There is a duty on anyone interesting in advancing genuine republicanism to do so in a peaceful way."
He referred to his party's ardfheis last January, which voted to recognise the police on both sides of the Border, and to his party's duty to hold the PSNI to account.
"We have lots of difficulties with the PSNI in terms of their delivery of services whether it is on hate crime, whether it is on burglaries and so on," he said. Republicans, he said, had "a duty to make it very clear [ the PSNI] should not be under attack".
Young people should be supported in their desire for a career in policing if that is what they wanted. "That is a choice for them which we would support," he said.