The incident happened at around 12.35pm in the Manorfield Drive area, near the Dublin/Meath border.
Gardaí had been called to the scene following reports of a man armed with a knife at a shop in Hartstown.
It is understood the man had threatened staff at a shop.
The man, who was in his late 20s, is believed to have then fled from the shop, threatening uniformed gardaí with a knife as he made his way home a short distance away at Manorfield Drive.
Gardaí say the less-than-lethal use of force options were unsuccessful, and a number of shots were fired from an official Garda firearm at around 12.35pm.
The man was treated at the scene by Armed Support Unit paramedics and Dublin Fire Brigade paramedics.
He was transferred to Connolly Hospital in Blanchardstown where he has pronounced dead this afternoon.
The Garda Síochána Ombudsman Commission have been notified of the incident and are currently in attendance at the scene.
Investigations are ongoing.
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— RTE NEWS.
