According to a radio broadcast, police received an emergency call to investigate the stabbing in the area of 350 Adams St. near Murkland Elementary School shortly after 4:20 p.m. Saturday.
An 18-year-old man was in a critical condition after another stabbing incident.
The brutal attack comes just hours after a 17-year-old boy was stabbed several times in Limehouse.
The unnamed suspect was arrested at the scene in Zenith Close, Colindale, north London, and remains in custody after the victim - thought to be a Romanian national - died in hospital that evening.
On another night, six people, including a 13-year-old boy, were stabbed in the space of 90 minutes.
This incident is believed to be the twelfth suspected murder case involving teenagers in the capital since the beginning of 2018.
A man in his 20s has been arrested on suspicion of murder over the Brixton death.
Detectives are informing his next of kin. When they arrived to the scene, they found the victim, Christopher Miles, dead.