One crew from Broughton, two crews from West Ashland and one crew from Newport Pagnell attended a water rescue incident.
Firefighters carried out a search of the river and riverbank following reports of a person in the water.
One adult male was receiving treatment from air ambulance clinicians and two further casualties had been rescued from the water prior to the arrival of the fire service.
Specialist water rescue crews entered the water to assist with the search, which was later supported by a Thames Valley police drone.
All persons were accounted for and were taken into the care of South Central Ambulance Service.