, officials said Tuesday.
Correctional Officer Eric Williams was working in a housing unit at the Canaan federal penitentiary when an inmate attacked him Monday night, according to prison officials. Other prison staff restrained the inmate, and Williams was rushed to a hospital where he was pronounced dead around 11:30 p.m.
"This is clearly the darkest day in our institution's short history, and we are in shock over this senseless loss of a colleague and friend," Warden David Ebbert said in a statement.
An autopsy performed Tuesday revealed that Williams, 34, suffered blunt head and neck trauma and multiple stab wounds and cuts. Lackawanna County Coroner Timothy Rowland ruled Williams' death a homicide.
Officials did not immediately release details of the attack, including the inmate's name, the kind of weapon or what, if anything, led to it.
"There was just no reason, no reason at all," Williams' sister, Lauren Williams, told The Associated Press. "There wasn't a mean bone in him. He was not confrontational at all. He's never been in a fight."
An FBI spokesman in Philadelphia declined comment, saying details would be released when the inmate is charged. It wasn't immediately clear when that would happen. The U.S. Attorney's Office in Harrisburg expressed condolences to Williams' family and colleagues, but declined further comment.
At least three inmates have been killed at the prison, which houses 1,350 high-security male inmates. A satellite camp houses 136 minimum-security inmates. The complex, about 20 miles northeast of Scranton, opened in 2005.
The last time a federal prison guard was killed on the job was June 2008 in Atwater, Calif., the Bureau of Prisons said.
Williams, from Nanticoke, began his career with the bureau on Sept. 11, 2011. His sister said he graduated from King's College with a criminal justice degree and worked in supermarket loss prevention and as a police officer before going to work in the federal prison system. "It was more of a stable job," she said.
She said they spoke nearly every day and he never reported any problems at work. In fact, "he said he was kind of bored sometimes," Lauren Williams said.
Eric Williams, who was single, loved to hunt, fish, play soccer and go bowling, and renovated a house near Lily Lake, a state-owned lake about 15 minutes from the family homestead in Nanticoke. In addition to his sister, he's survived by his parents and two other brothers.
"He had a joke for everything," recalled Lauren Williams, a senior at King's College. "He was in the wrong field. He should have been a comedian."
Of her brother's killer, Williams said: "He's already in jail. How do you get your justice?"