One woman was punched 28 times by a prison guard as she was pinned to the wall of her cell, trying in vain to shield her face from the next blow. She wound up with a concussion, a state investigator said.

Other inmates’ eyes were flooded with pepper spray before they had a chance to comply with orders shouted at midnight by correction officers dressed in riot gear.

Two supervisors who led the raids tried to cover their tracks by filing false reports at a chronically troubled women’s prison in New Jersey, the Edna Mahan Correctional Facility, according to the state’s attorney general, Gurbir S. Grewal.

On Thursday, three guards — including the two supervisors — were charged with crimes that carry mandatory five-year prison terms as part of a wide-ranging investigation into episodes that took place last month at the prison in western New Jersey.