Pupils turned to Twitter to post condolences to an 11-year-old classmate who died after she and her mother were hit by a car while waiting for a bus in Stanmore.
The crash happened at 12.20pm yesterday in The Common, Stanmore, between the junctions with Warren Lane and Wood Lane.
Police believe a Ford Fiesta was travelling northbound when it swerved and crossed into the southbound carriageway before colliding with pedestrians waiting at a bus stop, as well as a stationary 142 Watford Junction to Brent Cross bus.
The victim - 11-year-old girl Lily-Rose Murphy, who attended The Bushey Academy in Bushey, Hertfordshire - was pronounced dead at the scene and her 46-year-old mother was taken to hospital where she remains in a critical condition. The family lived in Stanmore.
Fellow pupils took to Twitter to express their shock at learning of Lily-Rose's death.
User @jackg4rvin posted: "RIP to Lily Murphy and hope her mum gets better, such a freak accident."
User @bethcumminsss wrote: "RIP to the yr7 girl from Bushey Academy that died today, didn't know her personally but still breaks my heart, another star up in the sky."
One of the tributes left at the roadside this morning reads: "Our little angel: RIP you're with the angels now. Love forever and never forgotten. Roo, Aaron, Faiza, Anna and family."
Andrew Hemmings, principal of The Bushey Academy, said: "It was with great sadness that we heard of the tragic loss of one of our students, Lily-Rose Murphy.
"Lily-Rose was a Year 7 student fully involved in all aspects of school life.
"She thoroughly enjoyed school and was seen by all staff as an exemplary student who embodied the proud to belong ethos of the academy.
"She was popular and hardworking and was an active member at the summer school that was run prior to her starting in Year 7 in September.
"She was also heavily involved in planning activities to raise funds for the academy's chosen charity.
"Our thoughts are firmly with the family and those closest to Lily-Rose and we are doing everything possible to support fellow students and staff.
"We have provided access to experienced counsellors and support workers to talk to those who are most affected."
A post-mortem examination on the 11-year-old conducted today at Northwick Park Hospital gave the cause of death as a broken neck, while an inquest will open in due course at North London Coroner's Court.
The driver of the Ford Focus - a 69-year-old woman who was the sole occupant of the vehicle - was cut from her car by the firefighters from the London Fire Brigade and remains in hospital with minor injuries.
No-one on the bus was injured and the passengers who saw the fatal crash are being urged to come forward alongside other motorists and passers-by to help officers compile a picture of the incident.
Detective Sergeant Chris Osborne, of the Road Death Investigation Unit based at Northolt, said: "We are appealing for any witnesses to this tragic incident to contact us.
"We are aware that there were a number of passengers on the bus involved, and a number of other vehicles in the vicinity.
"If you have any information we would like to hear from you so we can work out exactly what happened."
No arrests have been made, the police confirmed.
Arriva The Shires, which operates the bus hit by the car, said in a statement: "Arriva would like to pass on their deepest condolences to the family of the girl who tragically passed away yesterday.
" Our drivers and customers were witnesses at the scene and were deeply shocked by the accident.
"Our vehicles were stationary at the bus stop at the time so it is hoped the CCTV from them can assist the police with their investigation into what happened."
A tribute from Bushey Academy is expected to be released later.
n Anyone with information is asked to contact the Witness Line on 020 8842 1817.
