Thames Valley Air Ambulance has landed at a White Horse for an incident.
Emergency services responded to Dragon Hill Road, near Uffington, at around 12.30pm this afternoon (Thursday).
The red helicopter was seen landing close to the famous White Horse landmark to support paramedics already at the scene.
Drivers have been warned to avoid Dragon Hill Road, with one passerby reporting that an ambulance was blocking part of the road near the site. However, access to the main car park remained open.
UPDATE 2PM: Wiltshire 999s understands a man suffered a cardiac arrest, and has been taken to the Great Western Hospital for further care.
Whitney Parker, who assisted at the scene, said she was among those giving the man CPR.
She said: ‘I was one of the ladies giving this gentleman CPR. I really pray he’s going to be okay.
‘We all did our best and a massive well done to us all. It was really hard and difficult.
‘To the gentleman, we wish you a speedy recovery.’