An inmate was killed at Smith State Prison Monday but prison officials said it was not part of a wider disturbance.

Department of Corrections spokeswoman Kristin Stansil would not say how the inmate, whose name was not released, was killed.

No officers or other inmates were hurt, she said Tuesday.

All details were being withheld because "it's all part of our investigation," Stansil said. She said she did not know when the internal investigation would be completed.

Smith State Prison is a high-security prison in Glennville, west of Savannah, that holds more than 1,350 men.

The incident at Smith was the third in a week in the prison system, which has already put several institutions on heightened alert or lockdown because of inmate violence.

Over the weekend 12 inmates were hospitalized because of injuries suffered in a gang fight Friday night at Hancock State Prison in Sparta. The disturbance started in temporary structures where 250 medium-security inmates are housed, but it quickly spread to the main facility where violent inmates with long sentences are held.

On Nov. 21, a guard was injured and three inmates were hospitalized after a fight at Telfair State Prison in South Georgia.

Prison officials have said inmates are fighting each other over cellphones that are smuggled in.

But inmates who called The Atlanta Journal-Constitution Monday said the disturbances are only being coordinated with the help of cellphones and are protests of new prison rules.