Head teachers have been asked by police to try to keep pupils in education for as long as possible to help reduce the “epidemic of gang violence”.
Insp Daryl Lyon, who wrote to each school in Northamptonshire, said pupils at risk of exclusion could be referred to police for support.
There were 3,918 suspensions and 120 exclusions in the county in 2018.
Insp Lyon said: “We need to get involved with young people’s lives before they get stabbed or hurt.”
There were 13 murders in Northamptonshire last year, with the number of violent crimes increasing by 17.3% in the last year to a total of 19,246.
Gangs in Wellingborough have filmed themselves rapping about selling drugs and guns in videos posted online.
Insp Lyon said it was vital to manage the “epidemic of violence that we have seen across the county”.
“What I’m saying to schools is we need to keep people in the mainstream education for as long as possible because, if they are not, then no-one is keeping an eye on them,” he said.
“And we will support schools with their mission, especially if there is a gang concern.”
He said the information passed to them from schools would be used for safeguarding rather than law enforcement.
Urging schools to alert police to any pupils with “any form of gang link or concern”, he wrote: “Northants Police will use this data to ensure that every single child or family in the country linked in any way to a gang has the relevant support required to mitigate the risk in any way possible of gang violence to that family or child.”
Malcolm Arnold Academy, in Northampton, reduced its number of exclusions from 19 three years ago to none in the last academic year.
Nicola Koncarevic, head of the school, which teaches 11 to 18-year-olds, said it was about “creating open dialogues with different services and parents”.
She said this was intended to “make sure the outcome is what we want, which is the kids in school being educated”.