Police were called at 8.52pm on Sunday, 22 November to Westgate Street E8 following reports of a shooting.
Officers attended with colleagues from the London Ambulance Service and found a woman, believed to be aged in her 30s, suffering from a gunshot injury.
CPR was administered at the scene by officers prior to LAS arrival. She was then transported to an east London hospital; her condition is being treated as life-threatening.
Her next of kin have been informed.
There have been no arrests at this time.
A crime scene is in place and full enquiries into the circumstances are ongoing.
Any witnesses or those who have information that could assist police are asked to call 101 ref CAD 6587/22 Nov.
Alternatively tweet @MetCC, or to remain 100% anonymous contact Crimestoppers on 0800 555 111.