(CNN) -- A prison guard was fatally stabbed Friday afternoon in eastern Arkansas by an inmate already serving a life sentence for first-degree murder.
Sgt. Barbara Ester, 46, was trying to retrieve a pair of unauthorized tennis shoes from inmate Latavious Johnson about 12:30 p.m. when she was stabbed in the abdomen with a 6-inch metal shank at the East Arkansas Regional Unit in Brickeys, said Arkansas Department of Corrections spokeswoman Shea Wilson.
It was unclear how Johnson got the shoes, but anything not approved by the state is considered contraband, Wilson said.
"I don't know if he was angry or upset about something else and took it out on her, or if his actions were geared directly to her," Wilson said. "Our internal affairs and Arkansas State Police are on site and investigating the incident now."
The shank was made from a piece of metal that looked like something from an air conditioning unit.
Ester made it to the prison infirmary before collapsing on the floor, Wilson said. Ester was picked up by ambulance before being flown to the Memphis Trauma Center, where she died.
Johnson, 30, has had a number of disciplinary violations while in custody, Wilson said. He was convicted of first-degree murder in 2001 and has been in the Arkansas prison system since that August. Johnson will be moved at some point to the Varner Supermax Prison at Grady, in southeast Arkansas, because of Ester's killing, Wilson said.
"This is just a difficult thing. It's obviously a tragedy and very difficult time for the department," Wilson said. "We ask people to keep Sergeant Ester and her family and fellow officers in their thoughts and prayers."
Ester was a 12-year veteran of the Department of Corrections.
She is only the second officer to die at the hands of an inmate in the Arkansas corrections system, according to Wilson. The first prison guard was killed in November 1995 at the maximum security unit in Tucker.