A van left outside Aughnacloy police station on Thursday night contained a 300lb bomb, police have confirmed.
Hundreds of people are still out of their homes following the alert in County Tyrone. The bomb has now been made safe.
PSNI Superintendent Brian Kee said those behind the attack were "criminal terrorists".
He said if the bomb had detonated it would have caused severe destruction and loss of life.
"The intention of the people responsible for planting this bomb in the middle of the village of Aughnacloy is to murder police officers with no regard for the people who live in this community," the superintendent said.
"They completely ignored the fact that there could easily have been passers-by or nearby residents caught up and killed or seriously injured in an explosion.
"This is an outrage and should be condemned in the strongest possible terms by every right thinking person."
A large area around Aughnacloy PSNI station remains closed as army experts examine the white van which was abandoned at Dungannon Road on Thursday at 2210 BST.
About 350 people left their homes and spent the night in three halls.
Residents said the white van was left outside the PSNI station, the door was lying open and the engine was running.
Dissident republicans have been responsible for a number of car bomb attacks on police stations in Northern Ireland this year.
It is understood a burnt out car was found just over the border from Aughnacloy, in the Republic of Ireland. Police are liaising with Gardai (Irish police) to investigate a possible link.
They have appealed to anyone who may have seen the white van in the area, to contact them.
Some roads around the village remain cordoned off in the security operation and Aughnacloy Primary School has been closed for the day.
The main street in Aughnacloy is now partially open and the A5 is accessible, however the main Aughnacloy to Dungannon road is closed.
The alert was raised in a telephone warning to a Belfast newspaper office. It is believed the call was from dissident republicans and the caller used a recognised code word.
DUP councillor Sammy Brush said only an hour's warning was given and it was difficult, in that time frame, to get elderly people and young children out of bed and out of their homes.
He said the evacuation seemed "fairly well organised" and that there was "no panic".
"There's a little bit of anger and disbelief but I suppose the longer this goes on, the feelings will probably get stronger."
Sinn Fein MP for Fermanagh and South Tyrone Michelle Gildernew said those responsible for the device should "seriously reflect on what they are doing".
"The first thing to say is that people in Aughnacloy will be relieved this morning that no damage has been done and nobody has been injured in last night's attempted attack on the PSNI station," she said.
"However, people are angry at the disruption that has been caused particularly to elderly people and young children who were forced from their homes overnight.
"Their actions are no part of a campaign to bring about Irish unity and they have little or no popular support."
Ulster Unionist MLA for Fermanagh and South Tyrone Tom Elliott said it was "deeply distressing" such incidents were "becoming a familiar feature of life in Northern Ireland once again".
SDLP MLA Tommy Gallagher said: "Those who planted this device show a selfish contempt for the people of Aughnacloy who deserve to live their lives without fear of violence."