Gardaí are tonight searching for three raiders who held up a security van taking money to an ATM in Dublin this morning.
They escaped with what gardaí decribed as a "substantial amount of money" after the robbery at a petrol station on the Ballymun Road.
A Garda spokesman said the three men, one of whom was armed with a shotgun, pulled up at the petrol station on two motorbikes and confronted security staff.
One shot was fired during the robbery, which took place at 7.00am, but no injuries were reported. A security guard was hit on the head with the butt of the gun, although his injuries are not though to be serious.
One of the motorbikes was abandoned at the scene.
The three men fled on the second motorbike, which was later found on the southbound lane of the M50 between the Ballymun and Finglas exits.
Gardaí are examining the petrol station and where the motorbike was found.
Sitpu today called for a review of safety for cash-in-transit staff by unions, employers, Garda, the Private Security Authority and banks.
The union's security branch organiser, Kevin McMahon, said it was "wholly unacceptable" that staff should be put at risk. "We have to minimise the possibility of a repetition of such attacks and maximise protection of cash-in-transit security staff," he said.