Emergency services raced to a home in Vine Close, east London, just before 6.30pm after reports of a shooting.
Paramedics desperately tried to save the 42-year-old woman but she died at the scene.
A teenage boy, 16, and 20-year-old man were also rushed to a major trauma centre following the attack where their conditions are being assessed.
No arrests have been made at this time with a huge manhunt underway to catch the perpetrator.
Detective Superintendent Vicky Tunstall, from the local police team in Hackney, declared that whoever is responsible ‘will be brought to justice’.
She said in a statement: ‘This shocking incident has resulted in the death of a young woman and my thoughts are with her family at this incredibly difficult time.
‘My thoughts are also with the two people who have been taken to hospital.
‘Gun crime has no place on the streets of London and we will do all we can to bring whoever is responsible for this despicable crime to justice.’