Pupils are more vulnerable to being stabbed on their way home from school, a new study suggests.
The period immediately after classes end accounts for a large proportion of stabbings involving young victims, and these predominantly occur close to home and school, according to new research published in the journal BMJ Open.
The report follows widespread concern about violence on Britain's streets.
The authors highlight how the "incidence of interpersonal violence involving knives" has progressively increased in the UK in recent years.
The research team analysed data on 1,824 people aged 25 and under who had been treated for a stab injury at a London trauma centre over the course of 11 years.
Of these, 172 were children, 861 were aged 16 to 19, and 791 were aged 20 to 24.
Timings and locations of stabbings were collated from ambulance service data as well as information from the hospital trauma registry.
Between 2004 and 2014, the annual number of presentations for "assault resulting in penetrating trauma" increased by an average of 25 per cent each year.
Almost three-quarters (71 per cent) of victims were from poorer neighbourhoods, compared with just 1 per cent from richer areas.
The frequency of stab injuries rose sharply in the late teenage years, reaching a peak at age 18 before gradually declining.
Children were more likely to be stabbed on a school day than the older age group.
Among children, the researchers noted a "significant peak in frequency" between 4pm and 6pm.
Stabbings during this time frame accounted for 22 per cent of all child stabbings compared with 11 per cent in young adults.
Targeted policing and after-school clubs
On non-school days, incidents involving children were similar to those involving young adults in terms of what time of day the incident occurred.
Young adults aged 16 and over were more likely to be stabbed after midnight compared with younger victims.
The authors wrote: "In children, the spike in frequency in the late afternoon and early evening was attributable to incidents occurring on school days.
"The majority of stabbings in this time frame on school days occurred within 5km of home, which encompasses the average distance from home to school in children living in London."
This means that a "targeted preventative strategy" could help to reduce stabbings among youngsters, according to the researchers from Queen Mary University of London, London Ambulance Service, Newcastle University, Barts Health NHS Trust and South East Coast Ambulance Service.
They also called for better educational programmes to reduce violence.
"The sharp increase in stab injuries between the ages of 14 and 16 suggests that educational programmes and other preventative interventions are best delivered in primary or early secondary education," they wrote.
The researchers concluded: "We have shown that assaults resulting in penetrating injuries occur in distinct age-related patterns.
"Specifically, the period immediately after school accounts for a large proportion of incidents in children, and these predominantly occur close to home and school.
"This represents an opportunity for targeted preventative strategies in this population."
They highlight violence reduction schemes in Glasgow, which have resulted in declines in knife crime.
They said "aggressive law enforcement" coupled with a range of educational and behavioural programmes which raise awareness of the consequences of knife violence led to the success.
"This work shows that children and young people in London are at risk simply due to where they live and go to school," said one of the study authors, Karim Brohi, a consultant trauma surgeon at Barts Health, professor of trauma sciences at Queen Mary and director of the London Trauma System.
"A long-term multi-agency and community approach is needed if we are to change the culture of violence that now permeates deprived areas of London.
"Public health approaches to violence, such as with this study, can show who is at risk and allow the community and police to respond effectively – such as through after-school activities and targeted policing."
Lead author Paul Vulliamy, surgical registrar at Barts Health and clinical lecturer at Queen Mary, added: "We have demonstrated that there are age-specific epidemiological patterns of stabbings among young people, providing evidence for schools and children as specific targets for violence reduction strategies.
"We can reduce knife violence and unnecessary child deaths, but need long-term evidence-based interventions in education, policing, the community and at home."