A firefighter has died while on a training exercise at an Olympics watersports venue.
Alan Soard, 38, from Lowestoft, Suffolk, was taken ill in the water at the Lee Valley White Water Centre in Waltham Cross, Hertfordshire, on Tuesday.
Three ambulances and two air ambulances were called at about 11.30am, but attempts to resuscitate Soard failed.
A spokesman for Suffolk Fire Service said Soard had been a firefighter for 11 years and had no history of medical issues.
He was on a water rescue training course with colleagues from Lowestoft and Norfolk.
Andy Fry, Chief Fire Officer at Suffolk Fire and Rescue Service, said: "Despite valiant attempts, his firefighter colleagues and paramedics were unable to save his life.
"Of course, our thoughts at this very sad time are with Alan's family and friends and also with his firefighter colleagues who were with Alan at the time he was taken ill.
"Everyone has been stunned by these events. This is a devastating loss for Suffolk Fire and Rescue Service.
"We are a small fire service where people tend to know each other well and Alan had been a firefighter with us for over 11 years."
Soard served on White Watch at Lowestoft South fire station.
"He was highly regarded by his colleagues - he was an experienced, extremely professional and capable firefighter," said Fry.
"He loved his job and was well-respected by those who worked with him, many of whom also considered Alan to be a close friend.
"I want to pay tribute to the firefighters from both Suffolk and Norfolk who were with Alan yesterday and to our colleagues in the other emergency services who fought so hard to save his life."
He added that the fire service was working with Hertfordshire Police and the Health and Safety Executive to establish the full details of Mr Soard's "untimely death".