The badly wounded man, named locally as Gerry Hennessy, received serious wounds to the upper body and was airlifted by helicopter from the scene at Castleview Estate, Newcastle West, to Cork University Hospital.
His sister, Colette, who happened to meet him moments before the gunman stuck, was rushed to University Hospital Limerick with a hand wound.
Gardaí suspect that a gang run by two brothers, who control a drugs network in Newcastle West and Rathkeale, were responsible.
Sources in Newcastle West said Gerry Hennessy, who is in his 30s, left the area for the UK some years ago after a run-in with the gang brothers. One source said: “He only returned in the past week or so. It seems that be believed that the trouble he had with the brothers was in the past.”
In the attack described by gardaí as “opportunistic”, the gunman and his driver arrived in Castleview shortly after 3pm and parked a silver Passat a short distance from where Mr Hennessy was staying. As he walked towards the house, he met his sister, and as they talked, the gunman opened fire with a sawn-off shotgun.
Gardaí put road blocks and also began door to door inquiries. Forensic gardaí also combed the scene.
Gardaí last night were focusing their investigations on persons they believe were involved in the attack.
lGardaí have appealed for witnesses to contact Newcastle West Garda Station on 069 20650, the Garda Confidential telephone line 1800 666111 or any garda station.