Three boys aged 14 and 15 were arrested after a fight between masked gangs in Northampton town centre on Saturday night (May 21).
Detectives are appealing for witnesses in Mercers Row after the groups clashed at around 8pm.
A spokesperson said: “An altercation started in Mercers Row which led to a chase to Abington Street.
“Three of the males involved wore black puffer jackets and tracksuit bottoms and face coverings, including a surgical-style mask. Another male had on a bright orange tracksuit.
“Officers believe this area would have been busy with visitors to the night-time economy and would like to hear from anyone who saw any part of this incident.”
Two 15-year-olds and another boy aged 14 were arrested on suspicion of affray and released on bail pending further enquiries.
Witnesses or anyone with information which could help the investigation can call 101 using Incident number 22000291291 or contact Crimestoppers anonymously on 0800 555 111.