Officers and paramedics were called at around 5.30pm on Friday, September 30, to reports of an altercation in Tottenham High Road, near Holcombe Market, in Haringey.
Kane Ontre Zasheem Moses was found suffering what are believed to be stab injuries and died shortly afterwards.
A murder investigation has been launched following the teenager’s death and no arrests have yet been made.
Now the Met Police have said “there was also evidence of a firearm having been discharged”.
DI Daniel Catmull, who is leading the homicide investigation, said: “Although it is believed that the victim died of stab injuries, there was also evidence of a firearm having been discharged.
“This forms a crucial part of the police investigation, and detailed forensic work continues at the scene along with many other lines of enquiry.
“Local people have been coming forward to tell us what they saw and I am very grateful to them.
“However, I know there are more people who saw what happened or know information crucial to our investigation.
“I need those people to do the right thing and contact police or, if they wish to remain anonymous, they can contact Crimestoppers.”
He added: “My heart goes out to the family of this young man.
“They are being supported by specialist officers and I can assure them of my total commitment to finding and bringing to justice whoever was responsible for this brutal attack.”
Inspector Ismail Madari, from north London police, said: “[We] fully understand how upset local people will be by the violent death of such a young man on the streets of Tottenham.
“Just as my heartfelt sympathies are with the family and friends of the victim, I know that the community will be hurting too. We are here to help and support them.
“Dedicated officers will be conducting additional patrols in and around Tottenham High Road, and I urge anyone who has any information or concerns to speak with these officers. They are there to serve and protect you.”
Any witnesses or anyone with information are asked to call 101, ref 5327/30sep.
For those not comfortable in speaking to the police, Crimestoppers is a totally independent charity. They do not ask your name or trace your call.
Please contact them on 0800 555 111 or visit www.crimestoppers-uk.org to remain 100% anonymous.