On the day of the march some 10,000 people had gathered in Creggan Estate and proceeded towards Guildhall Square in the centre of the city. Paratroopers had sealed off the approaches to the square and the march organisers, in order to avoid trouble, led most of the demonstrators towards Free Derry Corner in the Bogside.
Groups of local youths stayed behind at the army barricades to confront the soldiers. Their orders were to move in and arrest as many of the rioters as possible. At 4.07pm 1 Para requested permission to arrest rioters. At 4.10pm soldiers opened fire on the crowd. Less than 30 minutes later 13 civilians were dead.
The soldiers claimed that they had been fired on as they moved in to make arrests. The people of the Bogside believed the army had summarily executed 13 unarmed civilians.