Police are hunting "would-be murderers" after a bomb exploded during an overnight security alert.
Officers were alerted to a device in Lurgan, Co Armagh, and during their search of the area another explosive went off.
Superintendent David Moore said the bomb was "significant and absolutely designed to kill".
He said: "It is my belief that the phone call and the first device were designed to lure police into the area to be targeted by the second device.
"This was a clear and unequivocal murder attempt on the policemen and women who serve the community in Lurgan."
The alert began with a call to the Samaritans yesterday claiming a device aimed at a police patrol during the early hours had failed to explode.
Homes were evacuated once the first device, which was not capable of detonating, was discovered and during a follow up search the second device detonated.
Police came under attack with petrol bombs and bricks during the operation.
"The professional, methodical and diligent way these same officers responded to this incident undoubtedly saved lives, their own and potentially those of local people who were placed in grave danger by the heinous criminals who planted this device," said Supt Moore.
"It is also disappointing that during this operation police officers were subjected to repeated attack with petrol bombs and bricks by a small and unrepresentative section of the community.
"That this should happen whilst police officers were already placing themselves at considerable risk in the interests of keeping local people safe is deeply regrettable.
"I have also been heartened, however, by the support we have received from a much broader section of the local community and those who properly represent them."
Supt Moore said a full investigation is under way and he appealed for witnesses to help identify "these would-be murderers".
John O'Dowd, Sinn Fein MLA for the area, said: "Those behind this alert are not representative of the people of Lurgan and should stop these pointless actions immediately."
Rail services between Belfast and Dublin were disrupted for a time because of the closure of the line between Lisburn and Portadown.