BLACKSBURG, Va. —  An inmate escaped from a hospital Sunday after wresting a pistol away from a deputy and fatally shooting an unarmed security guard, officials said. William Charles Morva, 24, remained at large Sunday, as officials searched for him on foot and in helicopters.

Morva, who was jailed on charges of robbing a deli, was taken to the Montgomery Regional Hospital emergency room in handcuffs and leg irons after he suffered a sprained wrist and ankle, Sheriff Tommy Whitt said.

He overpowered a deputy and took his pistol. Shots were fired, killing hospital security guard Derrick McFarland, 26, as he tried to help the deputy.

"We really need to look into it real closely and find out how this happened," Whitt said. "We have an idea, but it's just speculation at this point, and I'd rather not speculate."

The deputy, who was wounded in the struggle, was in stable condition Sunday afternoon but was sedated and could not speak with investigators.

The emergency room closed after the shooting and later reopened, said hospital spokeswoman Suzanne Barnette.

The Virginia State Police, Christiansburg police and the Montgomery County Sheriff's Office searched for Morva on foot and in helicopters.

Morva's trial on robbery charges had been continued twice this summer, and it was rescheduled for Wednesday, court records show.