Police were called to the incident at Hillingdon Street around 9.15 pm yesterday night (April 14).
The paramedics tried to save a 21 -year -old who had stabbed in the leg, but died on the scene.
Shortly after, five men and one woman, all in their 20 years, were arrested under suspicion of murder.
All of them remain in police custody while investigations are underway.
Those closest to the victim have not yet been informed of the news.
The County Commander Emma Bond leads surveillance in Southwark.
She said: “We understand that this news is shocking and disturbing for the community and that several crime scenes remain.
“Our continuous investigations and there will be a greater police presence in the area, I advise anyone in the community who has concern to talk to their local officers.
“I would also like to appeal to the public to obtain information.
“Please, if he saw, heard or has some footage after the incident last night, then come.
“Your information can significantly help our detectives with your research. You can do it by calling 101, referring to CAD 7392/14apr.”
Alternatively, to remain in anonymity you can call Crimeppers at 0800 555 111.
A spokesman for the London ambulance service said: “Yesterday they called us at 4.31 PM (Monday, April 14) for reports of an incident in Hillingdon Street, SE17.
“We send resources to the scene, including an ambulance team, a paramedic in a fast response car, an advanced paramedic, an incident response officer and the London air ambulance.
“The first of our teams arrived in four minutes. Our crews treated a man on the scene. Unfortunately, despite the best emergency efforts, he died, he died.”
