A 12-year-old boy injured in a stabbing is in a stable condition in hospital, police have said.
Officers were called to Mayfair Avenue in Pitsea, Essex, at about 13:55 BST on Monday to a reported assault.
The boy had a knife wound to his back after an argument and was taken by air ambulance to the Royal London Hospital.
Det Insp Sophie Hammonds said: "The boy is now in a stable condition in hospital, where he is being kept in as a precaution."
A girl and three boys, all aged 14, have been arrested on suspicion of causing grievous bodily harm.
Det Insp Hammonds said: "It's fortunate his injury was not more serious and we remain in touch with the victim and his family.
"We are progressing our investigation into the circumstances behind the incident and four teenagers remain in custody for questioning.
"At this stage we believe the victim was assaulted by people known to him following a verbal disagreement."
Basildon councillor Jack Ferguson said his thoughts were with the 12-year-old boy and his family.
"The community was shocked. We don't have incidents like this very often so when we do it makes it even more shocking. The community are looking for reassurance," he said.