A block of flats in Gibbs Crescent in Oxford has been cordoned off by police.
Two officers are currently stationed outside the flats.
Thames Valley Police spokeswoman Charlotte Redman said officers were called to Gibbs Crescent at 2.39pm to reports of an injured man.
He has been taken to hospital where he remains.
She added there was a scene watch in place and police were investigating.
South Central Ambulance spokeswoman Catherine Morrow said: “We were called at 2.29pm to a medical incident in Gibbs Crescent.
"We sent one ambulance to the scene and one patient, understood to be male, was taken to the John Radcliffe Hospital.”
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