Money earmarked for improving school security would be better spent on improving educational and mental health services for disaffected pupils, they say.
Michelle Elliott, director of the child-protection charity Kidscape, said: "After Dunblane the thing that scared me was that there were a lot of ticking timebombs out there, a whole lot of damaged people."
"We should be putting money into helping children with problems. We're becoming an uncaring society, in which young people will grow up and take revenge on us."
The warning comes in a week when pupil exclusions hit record levels, seven people were taken to hospital following a machete attack on a Wolverhampton infants' school and the inquiry into the Dunblane massacre ended.
The Government is promising "substantial" new money for school security soon. Psychologists argue that such cash would be better spent on disaffected children who, it is feared, could become tomorrow's violent adults.
Horrett Campbell, arrested on Tuesday in connection with the St Luke's attack, had a reputation for being a loner as an adult and was quiet and withdrawn at school.
An indication of the extent of disaffection came at a conference this week when researcher Carl Parsons of Canterbury Christ Church College revealed that 12,458 pupils were excluded in the 1994-95 school year, a rise from just under 3,000 a year in 1990. "Secondary schools are likely to face problems with the child, child and family health are likely to suffer and require medical treatment, crime is a distinct probability . . . and longer-term problems of adjustment are likely to continue into adulthood."
Ms Elliott, who is a school governor, said inadequate parents were bringing up more and more disturbed children. Teachers were not properly trained to deal with them, and matters were being exacerbated by the exodus of experienced staff.
"Given all that I'm surprised there are as few exclusions as there are. I think this is a nightmare scenario." Describing as "asinine" demands to turn schools into high-security institutions, she said the money would be better spent on good nurseries and good staff.
Peter Wilson, director of the charity Young Minds, said mental health issues should be incorporated into education. Money should be spent now while society was undergoing massive upheaval as a result of TV and changing family and work patterns. "We need to take preventative action," he said. Was Dunblane killer Thomas Hamilton, for example, spurred to act as a result of his earlier life?
Just 5 per cent of funding for mental health went to children. However, they made up around a quarter of those needing help and "we know adult mental health depends on what has gone on in children's lives".
Their views are shared by Peter Davies, who runs a pupil referral unit in Wiltshire and has complained that psychiatric services are so stretched that many children are not getting the help they need.
Michelle Elliott added: "Our children are behind high walls when they should be out and the people who are doing these things should be behind the high walls."