The Met said a further five people were arrested at addresses in Brent and Hounslow in connection with the fatal shooting.
They are all men – two aged 18 and the others aged 21, 24 and 33 – and remain in custody.
Ms Sadio had been attending a wake at the church.
She died at the scene, while two men, both aged in their 30s, were also injured, the force said.
Police said the gun was fired from a black Kia Niro with distinctive alloys.
Following the shooting, the car was driven to Barnhill Road where it was abandoned and set alight, the Met said.
