The London Air Ambulance landed on the site of the Heygate Estate on Wednesday afternoon after a man was stabbed at Elephant & Castle Shopping Centre.
Police cordoned off a section of the shopping centre at the side of the WHSmith store after the incident at lunchtime on Wednesday.
Blood-stained clothing could be seen on the floor of the shopping centre.
The victim is a man in his late 20s. He was taken to a South London hospital.
A police spokesman said the victim's injuries are not thought to be life-threatening.
He added that no arrests have yet been made and police inquiries continue.
Most of the centre's stores remained open, but customers were unable to reach some shops including Boots and Pricebusters.