An Early Intervention Foundation (EIF) report on the role of primary schools in preventing gang and youth violence found that teachers who were interviewed talked about doing "everything they could" to support vulnerable children while they were in school, but felt "frustrated and saddened" that it was not always enough.
The report found that some schools aimed to support vulnerable children with a wide range of interventions, including those offered by external providers as well as specialist staff, but others were heavily dependent on one member of staff, such as a learning mentor to deliver support.
It said it was also evident that some schools were very unclear about what services were available to them - either statutory or otherwise. Some schools had recently reduced their use of external providers due to budget reductions, noting this as a "lamentable loss".
Where external providers had been brought in to deliver support to pupils, they were found to have often selected on the back of informal recommendations, and commissioning of such services was rarely evidence-based.
"Overall, our interviews painted a picture of primary school staff who knew their children and families well, and who went above and beyond to try to provide strong, positive role models and to support children's emotional wellbeing," the report states.
"However, there was also a strong sense that some school staff were intensely frustrated and felt unsupported in their efforts to work with vulnerable children.
"Some staff expressed anger and sadness as they told us that they felt unable to change children's outcomes in spite of their best efforts."
The research found that primary school teachers and staff are well placed to identify children at risk of joining gangs at an early stage. It said that the role is especially vital as the average age of involvement in gang activity is falling.
But too often schools are not involved in wider local efforts to tackle gang crime and teachers and staff feel they lack the skills and knowledge to offer support.
Partnerships between schools and police were also found to be patchy, ranging from officers regularly visiting schools to having very little contact.
The EIF is calling for primary schools to be better integrated in local efforts to offer early help to children at risk of taking part in criminal activity. This includes working more closely with local police forces.
Schools also need more support to ensure they are running effective, evidence-based programmes to support children at risk of crime.
The findings are based on interviews with staff in six schools across the London boroughs of Lambeth and Wandsworth as well as voluntary sector providers involved in crime reduction.
"The providers we spoke to recognised that awareness within schools varied, and felt that teachers needed more training about the signs and implications of gang involvement," the report states.
"Participants did express a view that the average age of involvement in gangs was falling, and that early intervention with primary school-age children was crucial.
"There was a general consensus that children in these schools needed a higher level of pastoral care."
Previous research by the EIF has found that risk factors associated with gang involvement among children include aggressive behavior and having friends who are frequently in trouble. Such factors can be identified in children as young as seven years old.
"There is a clear opportunity to intervene earlier than we do currently on a key issue affecting children, and primary schools have an important role to play," said EIF chief executive Dr Jo Casebourne.
"The reality, starkly illustrated in our report, is that these opportunities are being missed. This is not a criticism of primary schools or teachers, who are supporting children to the best of their ability, in spite of the challenges they face.
"But it does mean that it is imperative that schools are given the information and tools they need to tackle the risks associated with gang and youth violence in an evidence-led way."