MCCOMB, Miss. (AP) — A Mississippi man stabbed his mother and grandmother in a federal government office Monday and was then shot to death by a security guard.

Pike County Coroner Jason Jones told The Associated Press that the slain suspect was Branen Carter, 21.

Carter was at the Social Security Administration office in McComb with his mother, Lee Anna Turnage, and grandmother, Ann Carter. Jones said another relative told him Turnage and Ann Carter had an appointment there and gave Branen Carter a ride. The family came from Foxworth, about 40 miles east of McComb.

Two witnesses said there was an argument between Branen Carter and Turnage before the stabbings.

Large numbers of law enforcement officers converged on the one-story brick building on the edge of McComb.

Ann Carter, 58, was in critical condition at Southwest Mississippi Medical Center in McComb hours after the stabbing, hospital spokeswoman Tina Brumfield said.

Brumfield said Turnage was taken by helicopter to the University of Mississippi Medical Center in Jackson. A UMMC spokesman, Marc Rolph, said nobody named Turnage was on the public registry of patients. A person’s name can be withheld from a patient registry for multiple reasons, including a request by relatives or law enforcement officials.