An air ambulance was called after a schoolboy became ill on the way to school.
South Wales Police said the teenager had become ill on Miskin Road, Pontyclun, on Wednesday morning.
He added that an ambulance and air ambulance had been called to the scene.
The Welsh Ambulance Trust said they were called at 8.13am to reports of a "medical emergency" on Miskin Road.
They sent two ambulances and a specialised medical car to the scene.
A spokeswoman said they were supported by Wales Air Ambulance, and he was taken to the University Hospital of Wales for treatment.
His condition is not yet known.
An eye witnesses said there was a heavy presence of emergency services near the grounds to Pontyclun RFC ground just before 9am.
A passing walker, who asked not to be named, said: "I was by the Co-op just before 9am when I heard the sirens and at least one police car cut very quickly into the rugby club.
"There was a helicopter overhead almost immediately afterwards and it came down very low but I don't think it actually landed.
"A few people in the street stopped to keep an eye on things but it wasn't clear what was happening. When I passed again about half an hour later there were two police cars plus an ambulance which had its lights on.
"I just hope it's nothing too serious and everyone is OK."
