Two British army soldiers have been shot dead in the North.
At least four other men have been injured in the attack which happened outside Masserene army barracks in Antrim.
They are all in a serious condition in hospital.
It is believed they were hit by shots from a passing car at approximately 9.20pm last night.
No-one has so far claimed responsibility.
The attack comes as Northern Ireland's chief constable, Sir Hugh Orde, defends his decision to order undercover soldiers back into the North to combat dissident republicans.
Taoiseach Brian Cowen and Foreign Affairs Minister Micheál Martin have condemned the attack.
The North's First Minister Peter Robinson has delayed plans to go the US in order to take stock of the situation.
The Secretary of State for Northern Ireland Shaun Woodward has also condemned the attack, calling it an 'act of criminal barbarism'.
He said the people who did it will be pursued, and will never be able stop political progress in Northern Ireland.