Two viable letter bombs addressed to senior police officers in Northern Ireland have been intercepted at Royal Mail sorting offices and safely defused within hours of each other.
A package containing a suspicious device addressed to Matt Baggott, chief contable of the Police Service of Northern Ireland (PSNI), was intercepted at a sorting office in northern Belfast in the early hours of this morning.
Army bomb disposal experts were called to Mallusk, Co Antrim, working through the night to make the device safe.
A second device, addressed to a high-profile officer whose identity has not been revealed, was later discovered at a delivery office in Lisburn.
PSNI assistant chief constable Will Kerr said it is thought that dissident republicans were behind both bomb attempts.
"We are very lucky we are not dealing with a fatality this morning," he told a press conference on earlier today.
"We will continue to deliver a policing service to the people of Northern Ireland irrespective of this threat.
"We have been very successful and we will continue to be successful in disrupting the activities of these small groups."
Police have confirmed that both packages contained a viable device.
The first device had been addressed to Chief Constable Baggott at the PSNI headquarters in Knock, on the edge of Belfast.
Speaking after it was made safe, Northern Ireland Secretary Theresa Villiers said those behind the letter bomb had no support.
"Those responsible for this device have almost no support and have demonstrated a blatant disregard for the safety of those who could have been injured by this callous and reckless attack," she said.
"The chief constable undertakes a challenging role in delivering community policing in a difficult threat environment.
"He and his officers have my full support and I am certain that the vast majority of people in Northern Ireland will condemn this disgraceful bomb attempt and others which have taken place over recent days," she added.
Both sorting offices had to be evacuated during the alerts, which each lasted several hours.
A spokeswoman for Royal Mail said there would be a knock-on effect with disruption of services throughout the day.
The threat from dissident republican extremists opposed to the peace process has been deemed severe by the Home Office.
Mr Kerr has also blamed dissidents for pipe bomb attacks on police vehicles in Londonderry and the outskirts of Belfast over the last three days.
He added that there had been a spike in attacks and attempts to kill police officers over the past month but declined to speculate on the reasons for the rise.
Northern Ireland's Justice Minister David Ford has described those responsible for the bomb attempts as "senseless".
Police in the province have appealed for the public to be vigilant and report anything that looks suspicious.