Police said all four dogs were of a Mastiff-type breed.
Supt Mitch Carr said: “I know this incident will have caused a lot of public concern, especially due to the young age of the children injured.
“Fortunately, it is believed that none of the injuries are life-threatening.
“The dogs have also been taken to police kennels while the investigation is ongoing.”
The London Ambulance Service said it sent crews including an advanced paramedic, an incident response officer and an air ambulance.
A spokesperson said the woman and two children were treated at the scene and taken to a major trauma centre by road.
The Met said extra officers would be in the area over the next few days to provide “community reassurance”.
