Gardai are investigating three separate aggravated burglaries at a social housing estate for older people in Dublin.
In one incident at around 9pm last Friday night, a male intruder forced his way into a house on Ballygall Road East in Glasnevin.
The intruder threatened and assaulted a man in his 60s at knife point before making off with a sum of cash.
Shortly after midnight on Tuesday night / Wednesday morning, the occupants of two houses in the same estate - a man in his 80s and a man in his 60s - were threatened at knife point by two male intruders, before being tied up.
The intruders escaped with sums of cash.
Forensic examinations are being carried out at the scenes to see if the incidents are linked, and no arrests have been made.