Police are appealing for information, after a report of a large group of people fighting in north east Hampshire.
Just after 18:30 GMT on Monday 25 May, officers and the Ministry of Defence Police were called to the incident at Hawley Lake.
No injuries have been reported and no arrests were made.
Shortly afterwards, police were called to a large group of males making threats in the Pinewood Park area of Farnborough, close to Hawley Woods.
Following searches by officers, no-one was found there - police have linked the two incidents.
Inspector Phil Mayne, from the Rushmoor Neighbourhood Policing Team, said: “We are working with the Ministry of Defence Police to establish the circumstances of what took place.
“Were you at Hawley Lake at around this time, and did you see what happened? Or perhaps you might have any other information that you think could help the investigation? If so, please get in touch.
“Our officers will be carrying out reassurance patrols in this area. If you have any concerns, please speak to them.”
Any witnesses are asked to call police on 101, quoting the reference number 44200186061.