A cordon was set up on St Agnes Road in Crumlin
A man has been taken into garda custody following an earlier incident in south Dublin.
A cordon was set up around St Agnes Church in Crumlin.
It is understood a garda negotiator was on site.
Two units of the fire brigade, an ambulance and several garda cars were at the scene - including unmarked garda cars.
Further details were not released for operational reasons.