The victim, in his 40s, died at the scene of the fight on a housing estate in Battersea earlier this evening.
Cops are now hunting the other brawlers, but no arrests have been made.
A spokesman for the Met Police said: "All other suspects had fled the scene prior to police arrival.
"A crime scene and cordons have been established.
"Enquiries are underway to establish the identity of the victim.
"At this early stage officers from South West Command Unit investigate.