Nuria Sajjad and Selena Lau died after a car crashed through a fence and collided with a building at The Study Prep school in Camp Road, Wimbledon, on the morning of July 6.
Several others were injured when the car crashed into the end-of-term tea party, all have since been discharged from hospital.
The Metropolitan Police said a 46-year-old woman from Wimbledon, who was arrested at the scene on suspicion of causing death by dangerous driving, has been has been re-bailed until January.
Inquests into the deaths of Nuria and Selena were opened and adjourned at Inner West London Coroner’s Court on July 12.
A Metropolitan Police spokesperson said: “Their families continue to request privacy at this difficult time.”
The girls died and 16 others were left injured following the crash.
10 people were taken to hospital following the incident.
A major incident was declared at the time, and people were urged to avoid the area, as a large cordon extending around the school was put in place by police.
In a statement directly after the crash, a spokesperson for the Metropolitan Police said: “We can now confirm that sadly a child has died following an incident where a car collided with a building at a school in Wimbledon.
“We can also confirm that the driver of the vehicle, a woman aged in her 40s, has been arrested on suspicion of causing death by dangerous driving
“There have been further injuries and we await an update from the London Ambulance Service.”
Detective Chief Superintendent Clair Kelland, local police commander for south-west London, said: “This is tragic news and our thoughts are with the girl’s family and friends, and everyone affected today.
“We remain at the scene and are continuing our investigation into the full circumstances of the incident.”
One witness outside the Wimbledon school said parents had collected their children, with some described as “distraught”.
Zac Powell, who did not give his age or address, told reporters: “I arrived at around quarter past 10, within 15 minutes of the incident happening.
“I saw a lot of distraught parents rushing from the scene on my arrival.
“Since then I have seen a lot of parents coming and picking up their children with expressions of relief or despair.
“There was quite a lot of damage I could see. Even from a distance.
“Within 15 minutes of my arrival there were armed police response units here at the scene.”
The MP for Wimbledon, Stephen Hammond, had said that the school is located in an area where “you wouldn’t see much speeding.”
In a statement when the crash happened, MP Stephen Hammond said: “Since being declared by the local police a major incident, you’ve seen that we’ve had fire, air ambulance, ambulance and police on the scene.
“Extraordinarily distressing and tragic incident on the last day of term.
“It appears just before 10 o’clock today, the police were called to the incident that a Range Rover drove into the school.
“There are a number of people who are critically injured as I understand it and given the scale of the response from emergency services… this is a very serious incident.”
He added that the school is a “very well-known and family-based school.”
“It’s a local prep school having girls between the ages of four and eight.” Mr Hammond added.