Officers attended Croydon High Street at 4pm on Wednesday, 27 October following reports of a stabbing.
London Ambulance Service also attended the scene. A man believed to be in his 20s was taken to hospital where his injuries were assessed as non-life threatening.
No arrests at this stage.
A Section 60 order has been put in place in Fairfield, Broadgreen and Selhurst between 5pm on Wednesday, 27 October and 5am on Thursday, 28 October.