Gangs of feral youths are rampaging in cities around the country, a senior police officer investigating an attack by a teenage gang has warned.
Mr Carroll had been working on his car outside his home
Chief Superintendent David Baines said the gangs "don't give a damn about the police or the criminal justice system".
His comments follow an attack on a father-of-four by youths he confronted outside his Greater Manchester home.
Phillip Carroll, 48, suffered serious head injuries after challenging the gang who had thrown a stone at his car.
Mr Carroll is critically ill in hospital following the attack near his house in Salford. His brother, John, said the area had been "terrorised" by youths.
The brothers were together working on the victim's Range Rover when the attack happened on Friday night at Grecian Street North in Lower Broughton.
John Carroll was with his brother when the attack happened
Mr Carroll has undergone two operations and is "critical, but stable" in Hope Hospital, police said.
John Carroll, 34, who witnessed the incident, said youths were a problem in the area but his brother "refused to let them get away with it".
He said: "I just keep remembering seeing Phil on the floor looking as though he was dying. Thankfully where he is now, at least he has got a fighting chance."
Ch Supt Baines said abusive and alcohol-fuelled gangs of young people all over the country are hanging around on street corners intimidating people and causing trouble.
"They then go on to damage property or, as we have seen with Mr Carroll, to commit a very vicious and unprovoked assault.
"They are feral, have no parental control or respect for anybody and are often fuelled by alcohol."
He said the force was targeting the 10 worst families in the area but added, "It is not just individuals, it is the whole family. They all lead a life of crime and are a corrosive influence on the area.
"I have spoken to parents who are unconcerned that their 14-year-old child has been arrested for a serious assault or robbery. But they are concerned that they might lose their house."