BELFAST, Northern Ireland - British Prime Minister Gordon Brown Monday met with military and political leaders in Northern Ireland in the wake of an attack that killed two British troops.

Meanwhile, Army officials said they would open an investigation into why there was no armed response to Saturday's shooting and why four soldiers walked unarmed out of a barracks days after the Irish terrorist threat level had been raised from "substantial" to "severe," The Times of London reported.

The attack killed two soldiers and seriously wounded two other soldiers and a pizza deliverymen on the road outside the base's main gate. A dissident faction that calls itself the Real IRA claimed responsibility for the attack in a telephone call to The Sunday Tribune, a Belfast newspaper.

Politicians in Northern Ireland said the weekend shooting outside a British army base in Antrim had the hallmarks of a bid by dissidents to destabilize the power-sharing government, The New York Times (NYSE:NYT) reported. The Real IRA has denounced the power-sharing government brokered in the 1990s.

Army and police officials confirmed no shots were fired in retaliation, The Times of London said. Army sources said Saturday's attack was the first time the Northern Ireland Security Guard Service had to deal with a direct confrontation on a base since taking over responsibility for barracks security more than 10 years ago.

An army spokesman did not tell the British newspaper what the security guards' rules of engagement were other than to say that they were allowed to fire in self-defense.

The soldiers were about to be deployed to Afghanistan.

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