An autistic 13-year-old schoolboy stabbed to death in a park on Sunday afternoon was “hilariously funny, charming and beautiful”, his family said.

Oliver Lucas Stephens, who was known as Olly, died at the scene of the attack at Bugs Bottom fields, Emmer Green, in Reading.

Four boys and a girl, aged between 13 and 14 and from Berkshire, are being held on suspicion of conspiracy to commit murder, Thames Valley Police said.

He always stood his ground and fought for the underdog whilst having an amazing depth of love, warmth and wit

In a statement issued through police, Olly’s family described the youngster as “an enigma” who “could get his own way with a wry smile and a cheeky grin”.

They said: “He always stood his ground and fought for the underdog whilst having an amazing depth of love, warmth and wit.

“In his final moments he must have been terrified. Fighting to get home, he had everything to live for.

“We now have only memories.

“An Olly-sized hole has been left in our hearts.”

The family described the ordeal as “every parents’ worst nightmare”.

But they also sought to highlight those who helped at the scene, including “a Good Samaritan that tried valiantly to save Oliver”, an off-duty doctor who offered help, and the emergency services.

Officers were called just before 4pm on Sunday following reports of a stabbing at the park, which is popular with dog walkers, joggers and families.

Parents laying flowers at nearby Highdown School called the killing “utterly senseless” and said their children who attended school with Olly were “devastated”.

Head teacher Rachel Cave said in a statement: “The Highdown community is reeling from the tragic news that a 13-year-old boy was stabbed in Emmer Green.

“This student was part of our community and many students and staff knew him well. For a life to be ended at such a young age is a total tragedy. Our thoughts and prayers are with his family.”

A dog walker told the PA news agency that she went through the park at around 3.30pm on Sunday and saw a group of youths standing near the woods, describing the scene as “slightly unusual”.

She said the park area had been “heaving” with joggers, walkers, metal detectorists and families in recent weeks.