WAYMART, Pa. — An inmate has killed a guard at a federal prison in northeastern Pennsylvania.

Prison officials say it happened Monday night at the Canaan penitentiary in Waymart, about 20 miles northeast of Scranton. Authorities say Correctional Officer Eric Williams was working in a housing unit when an inmate using a homemade weapon attacked him.

Williams was rushed to a hospital, where he was pronounced dead at 11:30 p.m.

Williams was from Nanticoke. He began his career with the Bureau of Prisons in September 2011.

The high-security prison has been placed on lockdown and an FBI investigation is under way.

Warden David Ebbert says, “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.”