The Bloody Sunday killings were unjustified and unjustifiable, the Prime Minster has said.
Thirteen marchers were shot dead on 30 January 1972 in Londonderry when British paratroopers opened fire on crowds at a civil rights demonstration.
Fourteen others were wounded, one later died. The Saville Report is heavily critical of the Army and found that soldiers fired the first shot.
Prime Minister David Cameron said he was “deeply sorry”.
He said that the findings of the Saville Report were “shocking”.
A huge cheer erupted in Guildhall Square in Derry as Mr Cameron delivered the findings which unequivocally blamed the Army for one of the most controversial days in Northern Ireland’s history.