Police have said a man aged in his late teens reportedly ran away from the spot where a booby-trap bomb was placed to target the PSNI.
A metal tube made to look like a used mortar was planted in Craigavon, Co Armagh, in a bid to kill police on Friday.
It was designed to explode if moved by officers lured into the area by fake reports.
Police received a report from a member of the public after a loud bang or explosion on Tullygally Road. The Irish News reported receiving a call claiming a mortar had been fired at police in the same area.
The call to the Irish News stated a "horizontal mortar was fired at a passed police patrol" on the Tullygally Road beside Aldervale flats but had "missed its target".
"So there is a live warhead in the vicinity," the caller warned.
Detective Superintendent Richard Campbell said the device was manufactured somewhere and asked anyone with information about activity in an outbuilding or garage in recent days or weeks to contact detectives.
He asked anyone who saw any unusual activity or vehicles acting suspiciously in the area of Tullygally Road on Friday night or in recent days or weeks to get in touch.
A suspicious person was seen running away from the area of the bus stop, near where the device was found, at around 11.45pm on Friday, the detective said.
The person was between 5ft 6in and 5ft 9in, of slim or medium build and believed to be aged in the late teens or early 20s.
The person was described as wearing a light grey or beige long-sleeved hooded top, with the hood up and face covered.
The suspicious individual was reported to have gone from the bus stop into open ground that borders the Tullygally Road, Aldervale flats and Drumglass estate in an area known locally as the Black Path.
Detective Superintendent Campbell said: "I believe the incident was staged in order to lure police into the area where a booby-trap device was placed and designed to explode if moved or touched.
"This was clearly designed to kill anyone who lifted or moved the device."
The detective superintendent added that someone knows where the device in question was manufactured.
"I would appeal to anyone who has any information about activity in an outbuilding or garage in recent days or weeks that may seem out of the ordinary to get in touch with detectives," he said.
"This device had to be transported to the area where it was planted and I am appealing for anyone who saw any unusual activity or vehicles acting suspiciously in the area of Tullygally Road on Friday night or in recent days or weeks to get in touch with us.
"I would appeal to anyone who saw this individual in the area or in the wider Craigavon area on Friday night or early Saturday morning to please contact my detectives.
"I ask that anyone who may be able to help our investigation and identify those responsible to call police on 101 and ask to speak to detectives in the Terrorism Investigation Unit in Castlereagh
"Or if you would prefer, information can be given anonymously via the independent charity Crimestoppers on 0800 555 111," the detective added.