Two men, believed to be from Northern Ireland, are in Garda custody in Monaghan town after a car chase in the area last night.
Three men, one believed to be armed with a handgun, had earlier staged a robbery at a parochial house in Armagh.
Two people were locked in a toilet at the house in Abbey Street before the gang searched the house, found a sum of money and made off in a van, said police.
PSNI officers alerted to the robbery gave chase and one man was arrested at Stilorgo Road in Benburb.
The other two men escaped in a white Northern-registered van which was later intercepted on the outskirts of Monaghan town.
Gardaí pursued the van from the Clontibret area of Monaghan across a back road to the roundabout where it drove over an embankment before crashing to a halt.
A Garda car was rammed on the main Dublin to Derry road near Monaghan town during the chase, but the garda occupants were unhurt.