A 13-year-old boy stabbed to death at a beauty spot has been named by police as Oliver Lucas Stephens.
The boy, known as Olly, from Reading, was attacked on Sunday afternoon at Bugs Bottom fields, Emmer Green, in Reading.
He died at the scene.
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.
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".
One card read: "Fly high Olly, love you loads, night night. We're all gonna miss you.
"Our angel Olly, gone way too soon, you didn't deserve this, in my heart forever."
Another read: "Dearest Olly, Taken way too soon, you were such a lovely lad. Loved by many. Thinking and sending love to your family at this sad time."
Rachel Cave, head teacher at Highdown School, 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."
On Monday, police stood guard at a large cordon surrounding Bugs Bottom fields, with forensics officers seen conducting searches and clustering around a small blue tent erected in the middle of an open field.
The scene is less than a mile from the school.
Matt Rodda, Labour MP for Reading East, told the PA news agency he was "deeply shocked" at the killing.
He said: "I offer my deepest condolences to this poor lad's family and friends.
"I was deeply shocked by it, apparently this poor lad was barely 13 years old.
"It's quite astounding really. It must have been truly dreadful to be here at the time.
"This is a very quiet area, a suburban area on the edge of town and typically on a Sunday afternoon, when the incident happened, you would have a lot of families, people walking their dogs in this country park, a well known beauty spot which is very quiet and pleasant."
Another dog walker told PA she went through the park at around 3.30pm on Sunday and saw a group of youths standing around near woods, describing the scene as "slightly unusual".
She said the park area has been "heaving" with joggers, walkers, metal detectorists and families in recent weeks.
Senior investigating officer Detective Superintendent Kevin Brown, head of Thames Valley Police's Major Crime Unit, said: "This remains a very active investigation and a large scene-watch remains in place.
"We have arrested five young people in connection with this tragic incident, but I would urge anybody who has any information surrounding what happened yesterday to please make contact with Thames Valley Police."
Police Federation chairman John Apter said of the incident on Twitter: "Horrific, so many lives will be shattered by this. Society does indeed need to take a look at itself."