Kieran Snee, 11, was playing at a recreation ground in Darlington, County Durham, when older children allegedly banged his swing seat against the construction's metal support in a game known as 'bumping'.
The little boy reportedly begged the children to stop as he was suffering head pains and nausea.
After staggering home, Kieron was taken to hospital where he collapsed and ended up in a coma and on a life support machine.
The Mirror reports that a girl of 15 was arrested on suspicion of grievous bodily harm and released on police bail after the incident.
Kirsty Bateman, mum of Kieran's cousin Jay who had been playing with him at the time, told the paper that Kieran had been 'crying' to be let off the swing: 'Jay told me one of the older boys said, 'Let him off' but one of the girls allegedly hit back: 'He's not had enough yet,'' she said.
Det Sgt Jim Cunningham from Durham Police said: 'We do not yet know if this was an accident or if there was horseplay involved.'
The play area was closed after the incident and the swing was taken down.
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