A man was airlifted to hospital with neurological injuries following a medical incident at Mote Park.
Paramedics from the helicopter were picked up by an ambulance after it landed at about 4.30pm.
At 5.20pm two ambulances and a response car returned to the Maidstone site and the man, was loaded into the back of the helicopter.
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He was taken to Kings College Hospital in London, which has a specialist neurological unit.
A Kent, Surrey and Sussex Air Ambulance spokesman confirmed they were dispatched at 4.20pm but could not give more details at this stage.
Witness Elena Cooper said it did not look like it had happened in the park itself but the helicopter landed by the cafe.
The park is busy at the moment, with families taking advantage of the sunshine during the school break.
South East Coast Ambulance Service has been approached for comment.
More as we get it.