Police investigating an alleged attack on a 15-year-old boy are appealing for mobile phone footage of the incident or events leading up to it.
The victim suffered three skull fractures in the attack at a Wiltshire secondary school on 11 January.
Three boys, aged 14, 15 and 17, have been charged with grievous bodily harm.
A Wiltshire Police spokesman said: "Police anticipate further significant developments in this case and anticipate further arrests shortly."
Two of the accused boys, aged 14 and 15, have appeared before magistrates and are due to appear in youth court on Monday.
A 17-year-old boy was remanded in custody at Swindon Youth Court on 15 January accused of grievous bodily harm.
He is due to appear again before the court on 22 January.
Six others have been released on bail, while an 18-year-old man has been released without charge.