Update 9.00pm: A security incident at Blanchardstown Shopping Centre in Dublin has ended.
Members of the Garda Armed Response Unit were deployed to search the centre at about 5pm, and have now been stood down.
The centre will remain closed for the night, but is expected to re-open as normal tomorrow.
Gardaí were responding to a reported sighting of missing Clare teenager Jack Dinan in the car park of the shopping centre.
Members of the Armed Response Unit swept the area twice and have now been stood down after the unsuccessful search.
An earlier garda statement said: "Jack is believed to be armed and the public are asked not to approach him, but should contact Gardaí at Ennis Garda Station on 065 6848100 or the emergency numbers 999 or 112."
Update 8.40pm: Armed gardaí are continuing a security operation at the Blanchardstown Centre in west Dublin this evening.
Much of the centre has been evacuated, shoppers have been turned away, and many local businesses have closed for the rest of the evening on Garda advice.
The adjacent Westend Shopping Park has posted on social media saying it is closed due to a security alert.
Local Sinn Féin Councillor Paul Donnelly says there is huge congestion around the approach roads to the centre.
"All of the roads into the centre are on complete lockdown," he said, saying no buses were allowed in either.
"A lot of people are walking from the centre out onto the periphery...Traffic is chaotic around the centre as people are trying to navigate their way out. Also, people who hadn't heard (about the alert) and who were heading to the centre are trying to turn around now and get back out (of the area)."
Gardaí are attending an incident at the Blanchardstown Shopping Centre in Dublin.
A number of armed gardai are at the scene, and the Garda helicopter is in attendance.
The centre has been evacuated, and shoppers are being turned away.
The incident is ongoing, and no further details are being released, for operational reasons.
Dublin Bus have halted services to Blanchardstown Shopping Centre at this time.
At the scene of a security alert at Blanchardstown Centre. Centre is being evacuated. pic.twitter.com/jtOGf28jt7— Paul Hosford (@PTHosford) November 1, 2017
— Claire Cunningham (@AuburnFilms) November 1, 2017