Up to 16 people were involved in an "altercation" in a supermarket car park in the Borders - leaving two of them injured.
The fight happened at about 03:20 on Sunday outside the Tesco store on Paton Street in Galashiels.
Police said a verbal dispute had escalated into physical violence.
A 21-year-old man was taken to Borders General Hospital with a serious leg injury. Another 26-year-old man suffered minor facial injuries.
Det Sgt Barry Roebuck said: "This is completely unacceptable behaviour and we continue to work to establish the full circumstances surrounding this incident.
"We'd urge anyone who may have witnessed this, or has any information which can help with our enquiries, to get in touch."