A 17-year old boy has died after being trapped in a storm drain in Witney.
Firefighters and paramedics battled to rescue two teenagers stranded in a culvert swollen by floodwater running underneath Eastfield Road.
Both were given CPR at the scene, but one later died a police spokesman confirmed.
The other remains in hospital.
After a day of heavy rainfall, eyewitnesses told of a "torrent" of water running off a hill, into a stream and through a metal grill, which takes floodwater underneath Eastfield Road, off Hailey Road.
The circumstances of the incident remain unclear, but those living nearby said children spent some of the afternoon playing in rising floodwater.
Ali Hagenan, 35, who lives nearby, said: "I went out when I saw the helicopter and five or six ambulances and fire crews, but we were all pushed back.
"I saw them come out of the water with a lad and they gave him CPR for a couple of minutes.
"It was shocking to see all this going on and our hearts must go out to all involved."
A South Central Ambulance Service spokesman said one of the teenagers was treated for suspected hypothermia.
Mike Poole, of Eastfield Road, said: "It gets ferociously deep out there.
"It had been absolutely chucking it down.
"I saw 30 to 40 firefighters and ambulance crew turn up and they were giving one of the kids CPR on the ground.
"I saw one come out on a stretcher and one being put into an ambulance."
One 45-year-old woman resident said: "I reckon there was about 50 children here yesterday afternoon, some on bikes and many in their school uniforms.
"The water was only a couple of feet deep but I did tell some of them not to play in it because I thought it was dangerous.
"A group of them went over the back (of the houses) and later I saw one come rushing back screaming for help." Another eyewitness said: "There were lots of kids playing out in the water - it looks like a couple got into trouble. I just hope the little lad I saw is all right."
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