Fort Stewart spokesman Kevin Larson says no one was hurt during the short standoff early Monday at the post's Winn Army Community Hospital.
Larson says the man was carrying four guns when he came into the hospital around 4 a.m. Monday and took the three workers hostage on the third floor. He says the gunman told them he wanted treatment for behavioral problems.
Brigadier General Jeffrey Phillips said the man grabbed a medic and took her up to the third floor, where behavioral healthcare is provided, reports CBS affiliate WTOC in Savannah, Ga. Phillips said the man took two more hostages - a senior nurse on call and another soldier who is an employee at the hospital.
The suspect's name has not been released.
"He's in custody. No shots were fired. There were no injuries," Phillips told WTOC.
The suspect is on base and is being questioned. He said he was unhappy with services provided there.
Winn Army Hospital was on lockdown for a short time, but has since reopened.
Larson says one of the hostages, an Army officer who is a nurse, helped police talk the gunman into surrendering peacefully.