Unarmed soldiers who tackled and subdued a gunman at a military base in Georgia on Wednesday have been hailed for their "heroism" and preventing deaths.

Brigadier General John Lubas said US Army personnel "immediately raced [towards] and attacked" the suspect when they heard gunfire, while US Army Secretary Dan Driscoll said they "ran into battle" to prevent further injuries and administer first aid.

Five people were injured when suspect Quornelius Radford, a 28-year-old US Army sergeant, allegedly opened fire at the Fort Stewart base. All the victims are expected to recover.

The suspect is in custody and officials said they would not speculate on a motive while an investigation was ongoing.

The suspect's father told US media the soldier sent a cryptic text message to a family member on the morning of the shooting.