The 18-year-old man shot in the head in Dublin early yesterday survived a previous murder attempt earlier this year in which his 22-year-old brother was shot and seriously injured.
Three men were arrested in Crumlin yesterday by gardaí investigating the shooting.
The three, all in their 20s, were being held at Crumlin and Sundrive Road Garda stations under Section 30 of the Offences Against the State Act. They can be detained for 72 hours without charge.
Yesterday's shooting took place at 2.10 a.m. as the 18-year-old was walking along Cooley Road in Drimnagh. No witnesses have come forward, although gardaí believe that a white van might have been in the vicinity at the time.
The attempted murder happened in the Garda sub-district of Sundrive Station, which now has one of the most serious problems with organised crime-related violence in the State.
There have been four assassinations and a spate of shootings and stabbings associated with the activities of organised criminals in the sub-district in the past year.
In February, the body of 22-year-old Niall Hanlon was found buried in the grounds of St Kevin's College, Sundrive Road. Hanlon, who is believed to have owed a drug dealer money, was repeatedly stabbed and mutilated.
In September another man, Declan Gavin (20), was also stabbed to death as he stood at a bus stop outside Crumlin Shopping Centre. He, too, is believed to have been a victim of the gang which killed Niall Hanlon and another man, David McGreevey, who was shot dead in Tallaght earlier this year.
Derek Lodge, a 26-year-old minor criminal from Drimnagh, was shot dead outside his home on Kilworth Road, Drimnagh, last May. He was also the victim of the local gang fighting. Exactly a year ago yesterday, one of Dublin best known criminals, Seamus "Shavo" Hogan (47) was shot dead outside the Transport Club, Clogher Road, Crumlin.
None of these murders has been solved.
The brother of the man shot last night was also critically injured after being shot in the bedroom of his house in the Drimnagh area in March.
The 18-year-old shot yesterday morning was in the house at the time his brother was shot but escaped through a back bedroom window.
The last shooting in the Sundrive sub-district was at the end of May, when a 23-year-old man was shot in the face as he answered a knock at the front door of his home on Crumlin Road in the early hours of the morning. The bullet passed through his cheek and tongue. He received hospital treatment.