He had apparently run away from a foot patrol after being stopped in the street for routine questioning. Members of the patrol chased him for some distance before at least one of them opened fire, fatally wounding him.
The incident plunged the Army into the latest of the recurring 'shoot-to-kill' incidents which nationalist representatives say have a serious effect on confidence in the security forces.
Some hours after the shooting a local road was blocked by protesters accusing troops of murder.
Previous incidents have been followed by complaints that soldiers involved have remained on duty, but the Army said yesterday that the troops would not be back on patrols until completion of an investigation.
Parts of the incident were seen by a number of people, who said they heard four shots. A man and a woman both said they had heard a soldier calling 'Halt' before opening fire. Although the man, Peter McBride, was only 18, he had two children, the younger only eight weeks old.
The RUC said a senior detective will investigate the shooting, while a military statement said: 'The Army sincerely regrets all loss of life, however caused, in the difficult circumstances within Northern Ireland and will be co-operating fully with the RUC's investigation.'
The local Sinn Fein councillor Joe Austin said the dead man had no republican connections, adding: 'There can be no justification for this brutal slaying of a young man whose only crime was his fear of those who killed him.' Mr McBride's father Peter claimed: 'He was just murdered. I think there was a warrant for his arrest. He was stealing - stealing, that's all. He was not a paramilitary.'
The incident is believed to have involved members of the Scots Guards. A month ago the regiment lost a guardsman who was killed by an IRA sniper close to yesterday's shooting. The RUC will be seeking to establish why the youth was running from the troops.
Some soldiers involved in similar incidents have been prosecuted, though most such cases have ended in acquittal. The decision on whether to prosecute centres on the question of whether they were justified in opening fire.
The 'yellow card' issued to soldiers states: 'You may only open fire against a person if he is committing or about to commit an act likely to endanger life, and there is no other way to prevent the danger.'
A friend of Mr McBride's, Margaret Reeves, told reporters she had been wheeling her child along the street in a buggy when she heard the sound of running. Turning round, she saw him running with soldiers chasing him.
She said: 'Peter was always being hassled by the police and the Army. One of the soldiers shouted 'Don't shoot, don't shoot', and I shouted 'Don't shoot'.' She said she was shouting 'Peter, stop, he'll shoot, stop', when Mr McBride ran round a corner. A soldier ran after him and she heard two shots, followed by a pause and two more shots.
Mr McBride staggered through a house and collapsed in a pool of blood at the back door of his sister's home. He died later in hospital. A number of wreaths were left in the blood-spattered doorway yesterday.
The Irish government said it was deeply concerned and would be pressing for a full investigation.