The teenage girl was found wounded by a bullet at Chalgrove Road, Tottenham on Monday night.
Despite the efforts of emergency services, she was pronounced dead at the scene an hour later.
In Walthamstow, a 16-year-old boy was found suffering from gun shot injuries and he is now in a critical condition.
A local resident said she heard multiple shots which sounded like a bomb exploding.
The shocking tally means the murder rate in London has risen by 40% in just three years; the stark opposite to New York's crime statistics which have fallen by almost 90% since Mayor Rudolph Giuliani's harsh crackdown in the 1990s.
"There are so many drugs, stabbings, and killings", she added.
"Her next of kin have been informed", the police said.
They were both taken to an east London hospital. The 16-year-old boy with bullet wounds is in a critical condition and fighting for his life. "One murder is one too many, and we are working hard with our partners to understand the increase and what we can do to prevent these tragedies from happening in the first place", a Metropolitan Police spokesperson said. In March, a 48-year-old Indian-origin logistics planner became a victim of a knife attack in the Southall suburb of London.
Croydon Central MP Sarah Jones, who chairs the all-party parliamentary group on knife crime, told the BBC's Today programme that the United Kingdom should follow New York's example in tackling violent crime. He was fatally stabbed moments after leaving a bar in Wandsworth and died on the street.
The incidents come as figures showed over the weekend that the murder rate in London has overtaken NY.