Officers on patrol came across a number of males fighting in Garratt Lane SW18 at around 4.58pm on Thursday, 29 October.
Two males were found near the Garratt Lane Burial Ground suffering from knife injuries.
Another male was found at the scene with a head injury.
Victim 1’s condition is being treated as life-threatening.
Victim 2 and 3’s injuries are not believed to be life-threatening.
Two males have been arrested in connection with the incident on suspicion of GBH and affray.
Road closures and an extensive crime scene are in place.
A Section 60 Order has been authorised for the whole of Wandsworth from 5.58pm.
Anyone who has information, video or images that could assist police are asked to call 101 ref CAD 5042/29 Oct.