Neighbours have been expressing their shock at Olivia's death.
One, Glenford Evans, said:
"She's a lovely mother and daughter. Everyone's really devastated by it. We just hope it's something that doesn't happen again to anyone.
"She was a beautiful little girl. Very quiet, very friendly. It's just absolutely awful."
Another, Temi Ismail-Sobogun, who has a two-year-old son, said:
"I'm gripping on to my son's pram now every moment. Even the wind today coming along the road today shows how easy it must have been to just go into the road."
More top news
Paramedics were on standby outside the police cordon as armed officers stood by the property.
A team of researchers has taken samples from the ten busiest London Underground lines to work out which are the dirtiest.
The action comes on top of an emergency timetable which has seen hundreds of trains a day being axed.