The attack proved at approximately 3.00pm in Kilclare Crescent, Jobstown.
The victim (17) was put forwarded to Tallaght Hospital where he was pronounced dead.
No arrests have been commanded as gardai investigate the killing.
The scene (above) is currently preserved for a applied examination.
Gardai wish to appeal to witnesses who may have been in the Kilclare stretch this afternoon between 2.45pm and 3.30pm to contact them at Tallaght garda spot on 01 666 6000, the garda Confidential Telephone Line on 1800 666 111 or any garda appoint.