A woman was rushed to the Darent Valley Hospital in a serious condition after collapsing in a shopping area in Dartford.
Paramedics and police were called to Market Street, the A226, just after 10.30am.
The woman was treated before being taken to hospital.
An ambulance service spokesman said: "We responded to reports a woman had collapsed.
"Ambulance crews attended the scene and the woman was treated before being taken to Darent Valley Hospital in a serious condition."
A police spokesman confirmed officers attended what they described as a medical incident to assist the ambulance crews.
A witness said the woman collapsed in Goodheads beauty salon and solarium but a spokesman for the company declined to comment.