FORT MADISON, Iowa (AP) — Iowa prison officials are facing renewed criticism from a union representing correctional officers following an attack by an inmate at the Iowa State Penitentiary in Fort Madison that left a staffer hospitalized.

Prison officials said in a news release that the inmate used a weapon in the Wednesday attack to strike the staffer several times. A statement later released by the union said the staffer was stabbed five times by an inmate wielding two 10-inch shanks. Prison officials said later Wednesday that the staffer was in stable condition in the hospital.

Danny Homan, president of the American Federation of State, County, and Municipal Employees Council 61, says the inmate is associated with a white supremacist prison gang, and that prison officials have ignored staff warnings that attacks by inmates were planned.

A Corrections Department spokeswoman on Wednesday declined to comment, citing the ongoing investigation.