Three girls remain in hospital after a car being chased by police mowed into them, killing a woman and a boy.
The suspected stolen car ploughed into the family as they walked along Lennard Road in Penge, south-east London, on Wednesday afternoon.
One distraught woman described how she tried to resuscitate the woman, named in reports as Rosie Cooper and thought to be aged in her late 30s, while the boy, believed to be her 10-year-old nephew Makayah McDermott, was initially conscious before passing out.
Two of the girls, twins named as Niyah and Yahla, Makayah's older sisters, were trapped underneath the car and managed to crawl out after bystanders lifted it off them.
But witnesses said another girl, aged around 11 and reportedly Cooper's daughter, screamed "I can't feel my legs" before being taken away in an ambulance.
Venissa Vassell, 18, who ran from a nearby railway station to help, said: "I did CPR on this lady. I blew in her mouth."
She added that the boy was fine one moment, but then "by the time I came back to speak to the little girl to say 'your brother is all right' he was passed out."
Makayah was reported to be a young actor - along with his sisters - and just last week had an audition for a part in a television series set in the 1950s.
Police are continuing to question a 23-year-old man who was arrested at the scene on suspicion of causing death by dangerous driving and theft of a vehicle.
Scotland Yard said neither of those who died had been formally identified and that post-mortem examinations are yet to be arranged.
The conditions of the three injured girls are unknown.
Scotland Yard said the Independent Police Complaints Commission (IPCC) has been informed and it will investigate the incident.