A member of staff at St Edwards School died near the boathouse on Port Meadow, the Oxford school confirmed.
Emergency services, including the Thames Air Ambulance helicopter, were scrambled to the common on Tuesday afternoon (October 11) after reports of the medical emergency.
The death is not being treated as suspicious by police.
In a statement, St Edward’s School’s warden Alastair Chirnside said the member of staff, who has not been named, had died at the scene despite the ‘best efforts’ of those present and the emergency services.
READ MORE: Live update as helicopter lands for Port Meadow emergency
The headteacher at the public school, where boarding pupils pay fees of £15,600-a term, said: “We wish to thank the paramedics for doing all that they could.
“This is a great shock for all of us, and it is a great loss for our school community. Most of all, it is a great sadness for their family: our thoughts and prayers and support are with them.
“As a school community we are supporting each other at this difficult time. Our pupils and staff are able to access the school’s pastoral network at any point.
“Thank you for respecting the privacy of our pupils and staff as we grieve for the loss of our colleague and friend.”
Emergency services, including police, fire and ambulance, were called to the moorings in Port Meadow in the evening at around 5pm.
A spokesman for Thames Valley Police said the force was called at around 4.30pm by the South Central Ambulance Service.
A spokesman said: "His next of kin are aware and they are being supported by officers.
"The death is being investigated as an unexplained, but non-suspicious death and a report will be provided to the coroner in due course."
Thames Valley Air Ambulance confirmed that its helicopter had been dispatched to the scene.
A spokeswoman said: “We can confirm that our helicopter was dispatched to provide advanced critical care at an incident at Port Meadow moorings yesterday afternoon.”
She added that the air ambulance would not be saying any further on the incident.
The air ambulance reportedly left the scene at around 5.45pm.
Last night, research analyst Mike Taylor, 58, from Wolvercote, said he was taking his rescue dog Milla out for their evening walk when they saw the blue lights of the fire brigade and the air ambulance helicopter.
“I’ve been doing this walk [on the meadow] every night for 20 years and it is the first time I’ve seen anything like that,” he told the Oxford Mail.
“Milla’s never seen anything like it either. She didn’t even bark. I assumed she would have started barking as soon as she saw the helicopter take off. I think she sensed the mood.”
Mr Taylor said: “It’s a great tragedy. The kids on the river and the teachers with their megaphones are a feature of this part of the river. It wouldn’t be the same place without them.”
He added: “I thought it was a training exercise because the fire brigade often trains at the top of the meadow, so blue lights are not a big surprise.
“But there was a big surprise.”
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