Murder probe detectives investigating the hit-and-run death of a 12-year-old boy as he left school believe the suspect may have planned a similar attack nearby moments earlier.

Essex Police said they received reports of a car mounting the pavement near Roding Valley High School in Loughton roughly 10 minutes before a vehicle ploughed into children outside nearby Debden Park High School at 3.20pm on Monday.

A 12-year-old boy, named locally as Harley Watson and described as a “little man with a big heart”, suffered fatal injuries while six others – including five children – were injured.

A 51-year-old man remains in police custody on suspicion of murder, attempted murder and other motoring offences.

Hit and run outside Essex school
A woman leaves a floral bouquet at the entrance to Debden Park High School, in Willingale Road, Loughton (Rick Findler/PA)

The force said on Tuesday it had “voluntarily referred itself to the Independent Office for Police Conduct (IOPC) based on previous contact between the force and a 51-year-old man arrested” but said it was unable to give further details.

Discussing the second reported incident, Detective Chief Inspector Rob Kirby said: “The incident near Roding Valley High School, believed to have happened in Brook Road, was reported to us after it became widely known we were dealing with a serious collision in Willingale Road.

“Our investigations have led us to establish that there may be connections between that incident and the one which has led us to establish a murder investigation.

“I am appealing for anyone who witnessed that incident to contact my team. I would also like to hear from anyone who saw a silver Ford Ka travelling through Loughton between 2.40pm and 3.45pm yesterday to contact us, particularly if you have any CCTV or dash cam footage.”

Mr Kirby said the suspect was arrested in a vehicle in the car park of the Merry Fiddler pub in Fiddlers Hamlet at 11pm on Monday, and appealed for anyone with information or dash cam footage to contact police.

Hit and run outside Essex school
Tributes left near the entrance to Debden Park High School, in Willingale Road, Loughton, Essex (Rick Findler/PA)

The man is being held on suspicion of murder, six counts of attempted murder and one of causing death by dangerous driving.

He is also accused of six offences of causing serious injury by driving, failing to stop at the scene of a collision and driving without insurance.

The arrest came after detectives appealed to find Loughton man Terry Glover over the incident.

The Rector of Loughton, Reverend Chris Davies, spent on Tuesday morning at the school where Harley was a pupil, a church spokesman confirmed.

It came as tearful parents and pupils laid dozens of floral bouquets near the entrance to the school.

One, from a friend named Edith, said: “Dear Harley, I will miss you so much! Forever be in our hearts. Fly high.”

A football inscribed with handwritten messages including “sleep tight little man”, and “little man with a big heart” was also left in tribute.

Head teacher Helen Gascoyne said the school had been “devastated” by the death of one of its students, and that pupils would be offered counselling on Tuesday.

Hit and run outside Essex school
People carrying flowers arrive at Debden Park High School to pay tribute to Harley Watson, 12 (Rick Findler/PA)

A large cordon remains in place as detectives continue to search for clues, while scores of well-wishers have begun donating to a GoFundMe.com fundraising page in his memory.

Two 15-year-old boys, a 13-year-old boy, a 16-year-old girl, a 12-year-old boy and a 23-year-old woman were left injured after the crash, Essex Police said.

Debden Park is a mixed academy school for pupils aged 11 to 18, which specialises in the performing arts and received a rating of “outstanding” in its most recent Ofsted inspection, according to its prospectus.