ANTRIM, Northern Ireland (AP) – Catholic and Protestant congregations prayed together for peace Sunday after IRA dissidents killed two British soldiers as they collected pizzas – the first deadly attack on Northern Ireland security forces in 12 years.

The leaders of the territory’s Catholic-Protestant administration warned that Irish Republican Army dissidents were trying to tear apart their young coalition and drag Northern Ireland back toward its bloody past. The leaders postponed a U.S. trip to deal with the crisis but expect to meet with President Barack Obama on St. Patrick’s Day as planned.

Police said two dissidents with assault rifles opened fire Saturday night from a car as four soldiers – who were just hours away from being deployed to Afghanistan – met two Domino’s Pizza delivery men at the entrance of the Massereene army barracks in Antrim, west of Belfast.

All four were wounded, two fatally. Also shot were the two delivery men, a local teenager who was seriously wounded and a 32-year-old Polish immigrant left in critical condition.

An Irish newspaper, the Sunday Tribune, said it received a claim of responsibility in a phone call from the Real IRA splinter group.

The newspaper said the caller defended the shooting and described the pizza delivery men as “collaborators of British rule in Ireland.”

The Real IRA was responsible for the deadliest terror attack in Northern Ireland history: a 1998 car bombing of the town of Omagh that killed 29 people, mostly women and children.

The senior Catholic in the power-sharing coalition, Deputy First Minister Martin McGuinness, said dissidents were trying to rekindle sectarian bloodshed and force Britain to resume sterner security policies. McGuinness, a former IRA commander, called the violence “absolutely futile.”

The IRA killed nearly 1,800 people from 1970 to 1997 in a failed effort to force Northern Ireland out of the United Kingdom and into the Republic of Ireland. The IRA disarmed and renounced violence in 2005, but several shadowy splinter groups have tried to continue the campaign.

Both McGuinness and First Minister Peter Robinson, the Protestant leader of the 22-month-old coalition, vowed that the attack would not weaken power-sharing, the central accomplishment of the U.S.-brokered Good Friday peace accord in 1998.

Robinson and McGuinness postponed a U.S. trip, canceling meetings scheduled to start Monday with several American businesses operating in Northern Ireland. But they still expect to visit Obama at the White House on St. Patrick’s Day, March 17, when Northern Ireland leaders traditionally seek American political and economic support.

Robinson urged Protestant extremists not to retaliate against the Catholic community. Two outlawed Protestant groups, the Ulster Defense Association and the Ulster Volunteer Force, claim to have renounced violence but have refused to disarm – because they reserve the right to seek revenge for dissident IRA acts.

“Can I urge all of those who may be angry within the (pro-British) unionist community – this is a matter to be left entirely with the police and the authorities,” Robinson said.

Catholic and Protestant congregations in Antrim walked at midday from their churches to the scene of the killing, where police forensic specialists were still searching the ground for bullet fragments.

Ministers from the Catholic, Anglican, Presbyterian and Methodist churches took turns praying for the dead and wounded, for the IRA dissidents to give up, and for their often-bickering leaders to stay on a path to reconciliation. The crowd reached several hundred.

Passers-by left floral tributes and handwritten messages. “Real men who carry guns wear a uniform … Cowards do not,” one read.

In Washington, a spokesman for U.S. President Barack Obama condemned the attack.

“Those who perpetrated these cowardly acts do not represent the will of the people of Northern Ireland, who have chosen a path of peace and reconciliation,” said Mike Hammer, spokesman for the White House’s National Security Council.

Police commander Hugh Orde – who had warned of an imminent dissident attack – said he was certain he could keep British troops off the streets, a key peacemaking achievement maintained since 2007. More than 4,000 troops are based here but train exclusively for overseas deployments and are rarely seen in uniform in public.

On Saturday night, scores of Corps of Royal Engineers soldiers based at Massereene ordered pizzas – a final feast before boarding a flight to Afghanistan for a six-month tour. The four soldiers were already wearing their desert camouflage fatigues when they met the two delivery men.

Police Chief Superintendent Derek Williamson, who is leading the hunt for the killers, said all six were believed wounded during the initial volley of bullets, then the gunmen got out of their vehicle and shot their victims again as they lay on the ground.

Police said the attackers must have noticed that unarmed soldiers were in the habit of walking to the base gates to collect fast-food orders. Orde said the soldiers and pizza men had no idea they were targets because Northern Ireland has become “a far more normal and safe place to live.”

Williamson identified the two fatal victims as Royal Engineers in their early 20s but declined to reveal their names. The rest of their unit departed Sunday for Afghanistan after giving statements to police.

Police later found the attackers’ getaway vehicle in the nearby town of Randalstown. No arrests were reported.

The dissidents have ratcheted up their violence since November 2007, when they shot two policemen in the face with shotgun blasts. Both survived. Several more police officers have been wounded in more than a dozen rocket, bomb and gun attacks since – but until Saturday, efforts to attack army installations had fizzled or been intercepted by police.

The Real IRA’s claim of responsibility Sunday appeared consistent with its recent threats to target civilians who conduct business with British security forces. For decades, the IRA similarly reserved the right to kill anyone who worked or provided supplies for police and soldiers.

The Real IRA last killed someone in 2002, when a Protestant construction worker died after opening a booby-trapped lunch box while he was working in a derelict army base. The splinter group had not killed a member of the British security forces before Saturday’s attack.

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