Safety concerns and allegations of bullying are being raised by parents, ex-staff and a former governor at a Special Education Needs (SEND) school.
More than 60 people signed an open letter to the council calling for an investigation into the Heart of the Forest school in Coleford.
Complaints include pupils coming home with bruises, missing teeth, and being forced to sit in soiled underwear.
The school said safeguarding students was a "top priority".
In the letter, the group said they had "grave concerns" the school was putting the "safety of children at risk", leaving them "too scared to go into school".
Sam took his autistic and non-verbal daughter out of the school in December after a number of "worrying incidents".
He claimed she came home with bruises on her face which the school could not explain or provide incident reports for.
