Family pay tribute to "good, kind, helpful and lovely boy" killed in hit and run outside his school
Harley, 12, died in hospital after a vehicle ploughed into children who were leaving Debden Park High School, in Loughton, Essex, at 3.20pm on Monday.
Murder probe detectives believe the suspect may have planned a similar attack nearby moments earlier after they received reports of a car mounting the pavement near Roding Valley High School in Loughton at around 3.10pm.
Harley died in hospital from his injuries and six others - including five children - were also hurt in the crash on Willingale Road.
A 51-year-old man remains in police custody on suspicion of murder, attempted murder and other motoring offences.
In a short statement released through Essex Police, Harley's family said: "We are so devastated by what has happened.
"Harley was a good, kind, helpful and lovely boy.
"We would like to thank everyone for their kind wishes and concern. However as a family we would like people to respect our privacy and allow us to grieve in peace."
Scores of well-wishers have begun donating to a GoFundMe.com fundraising page in his memory, which has so far raised more than £10,000.