Attorney General Gurbir Grewal says four senior correctional officers have been charged with assault and misconduct stemming from a January attack on female inmates at New Jersey’s only women’s prison.

That brings to eight the total number of guards charged at Edna Mahan Correctional Facility for Women in Clinton. The charges stem from an investigation led by the attorney general’s office and county prosecutors into what they said was a January attack on inmates.

“We continue to pursue all evidence and leads in our ongoing investigation,” Grewal said in a statement. “I promised to hold everyone accountable who played a role in this horrific incident, at any level of the prison’s hierarchy, and we’re working hard to meet that promise.”

Officials say that anyone with information about the incident should call 1-844-OPIA-TIPS to “ensure that all who bear responsibility are brought to justice.”