The Provisional Irish Republican Army (IRA) carries out an IED roadside bomb attack at the Killylea Road on the outskirts of Armagh, County Armagh, Northern Ireland, on July 24, 1990. An IRA active service unit detonates a large bomb as an unmarked Royal Ulster Constabulary (RUC) vehicle and a civilian car pass, killing three RUC officers and a Catholic nun.

Leading up to the attack, on April 9, 1990 four Ulster Defence Regiment (UDR) soldiers (Michael Adams, John Birch, John Bradley, Steven Smart) are killed in a similar attack when the IRA detonates a land mine under their patrol vehicle on Ballydugan Road, Downpatrick, County Down. The land mine contains over 1,000 lbs. of explosives.

On the afternoon of July 24, 1990, 37-year-old nun Catherine Dunne is driving an Austin Metro car with a passenger, Cathy McCann, a 25-year-old social worker. Some hours previously, members of the IRA take over a house close to Killylea Road, two miles outside Armagh, County Armagh, holding its occupants, a married couple and their children, at gunpoint.

A detonating wire is placed from the house to a 1,000 lb. bomb, placed in a culvert under Killylea Road. At approximately 2:00 PM, as Dunne’s car is driving to Armagh, a Royal Ulster Constabulary patrol car is traveling in the opposite direction. Dunne’s car passes by the patrol car just as the police drive over the culvert, at which point the IRA detonate the bomb. Constable William James Hanson (37), and reserve officers Joshua Cyril Willis (35) and David Sterritt (34), are all killed instantly. Their car is blown into the air and lands upside down. Dunne and McCann are both severely injured with Dunne later dying of her injuries.

Witness Paul Corr, owner of a petrol filling station nearby, says, “The ground shook beneath us and it was accompanied by a very large explosion. At first we did not see the police car. The whole place was a terrible mess. Then we saw two young girls in the [Austin Metro]. They were unconscious and looked in a pretty bad way. There was nothing we could do for the policemen. Nobody could have come out of that car alive. It was dreadful.”

The bomb leaves a 20-foot-diameter crater in the two-lane road.

Taoiseach Charles Haughey is quoted as saying, “I know all the people of Ireland join me in my condemnation of this atrocity.”

The IRA releases a message claiming responsibility for the attack, and calls Dunne a victim of “unforeseen and fluke circumstances.” The statement is rejected in advance by political and Catholic and Protestant leaders alike and politicians in Ireland and Great Britain.

Sinn Féin‘s Martin McGuinness says, “Our sorrow at these deaths is genuine and profound, but will be abused by our political opponents who will cynically exploit yesterday’s events for their own political purpose.”

Pope John Paul II sends a message to be read at Dunne’s funeral in which he condemns the “grievous injustice and futility” of the murders that leave him “deeply shocked and saddened.” He implores “the men and women who espouse violence to recognise the grievous injustice and futility of terrorism.”

Two men, Henry McCartney (26) and Tarlac Connolly (29), are charged with the killings. They are later given life sentences but are released in 2000 under the terms of the Good Friday Agreement.