Two 16-year-old boys and a 15-year-old boy were arrested on suspicion of murder and taken to an east London police station where they remain in custody, a Scotland Yard spokesman said.
Police are standing guard outside the terraced house where the shooting happened. The street, which backs on to Wick Woodland, remains closed to allow detectives to carry out their inquiries.
Mourners visited the scene throughout Sunday to lay flowers and leave messages of condolence.
Earlier in the week Shereka had been pictured in the local press helping to host the Jamaican high commissioner who visited The Urswick school where she was a student.
Anyone with information is asked to call Crimestoppers on 0800 555 111.