Planks of wood, baseball bats and metal poles were used in an altercation between two groups of people in Furzton on Wednesday, and there was a report that a firearm was discharged.
It happened close to the Furzton Lake pub at around 6.40pm.
One of the groups disembarked from a black van, while the other was on foot.
“Fortunately this type of incident is rare in Milton Keynes,” said Supt Gez Chiariello, LPA Commander for Milton Keynes.
“I would like to reassure the public that this type of behaviour will not be tolerated and we will do all we can to bring those responsible to justice.”
Investigating officer PC Tim Goodridge added: “This was an incident involving two groups of people who were reported to be carrying weapons. It was also reported that a firearm may have been discharged during the incident.
“I would appeal to anyone who believes they may know the identity of anyone who may have been involved in the incident to come forward and speak to the police on the non-emergency number 101.”
Nine people from Milton Keynes have been arrested in connection with the incident.