Dissident republicans have attempted to kill police officers responding to a report from the public, a senior officer in Northern Ireland said.
Investigators believe a viable explosive device discovered in Craigavon, Co Armagh, represented a failed bid to target members of the Police Service of Northern Ireland (PSNI) overnight on Friday into Saturday morning.
Chief Superintendent Peter Farrar said detectives were keeping an open mind on whether something had been fired but added that elements of the device were designed to murder officers.
He said: "I cannot condemn strongly enough those behind this cowardly and evil attack of terrorism.
"They offer nothing but heartache to this community and their actions here do not reflect the wishes of the vast majority of the good people living in this area.
"Huge disruption has been caused to the lives of those residents who live nearby, with people being evacuated from their homes in the middle of the night."
At around midnight police received a report of a loud bang in the Tullygally Road area.
A short time later the PSNI was contacted by a Belfast-based newspaper reporting that it had received a call claiming a device had been fired at a police patrol but had missed its target.
Officers and bomb disposal experts from the Army responded and a suspicious object was discovered, and later confirmed as a viable explosive.
Mr Farrar said: "We believe that this attack was set up in such a way as to target local police officers responding to the area following those reports from the public."
Twenty people were evacuated, including a pensioner aged 80.
Renegades who oppose the peace process have killed police officers, soldiers and prison officers in Northern Ireland, and parts of Craigavon have been a hotspot for dissident activity in the past.
Mr Farrar said: "Clearly this was a lethal device designed to murder police officers or indeed any member of the public, whether they be an older person or a child who would have been in the vicinity of this."
He confirmed the police focus is on dissident republicans.