An Alabama inmate who attacked a female guard at a rural prison died of injuries he received while being restrained by other officers, prison officials said Thursday.

The death of Rocrast Donnell Mack, 24, is being investigated by the Alabama Department of Corrections and the Alabama Bureau of Investigation, said prison spokesman Brian Corbett.

Corbett said Mack attacked an officer inside Ventress prison on Aug. 4. Other officers responded to help the woman, he said, and Mack was fatally injured while being restrained. He later died at a hospital.

"He continued to fight and resist," Corbett told The Associated Press. Corbett would not say how many officers were involved or elaborate on Mack's injuries because of the ongoing investigation.

A prison activist said Mack's relatives, most of whom live in nearby Eufaula, suspect officers beat the prisoner to death.

"All of them are feeling like some foul play went on," said Kenneth Glasgow, a pastor and head of the Ordinary People Society in Dothan. He said he planned to investigate.

The female officer's injuries were not life-threatening, Corbett said. It was unclear if any other officers were hurt.

Prison records listed Mack as being 5-foot-11 and weighing 160 pounds. He was sentenced to 20 years in prison in February for a drug conviction in Montgomery County.

Ventress, in southeast Alabama, was one of state's most overcrowded prisons this spring, the latest period for which statistics are available on the prison system's website. Originally designed for 650 men, the medium-security prison held 1,668 prisoners at the end of April.