The soldier from North Carolina was pronounced dead at Providence Hospital, according to Fort Jackson commander Brig. Gen. Milford Beagle, Jr. Hospital staff said the death was not heat-related, according to base officials.
"The tragic loss of a soldier, our nation's most precious resource, is devastating to the families, friends and teammates," Beagle said.
The soldier-in-training was "preparing to do physical training in his battalion area" when he died, Fort Jackson said in a separate statement.
"Our deepest condolences & support to the 3rd Battalion, 60th Infantry Regiment 'River Raiders' on the loss of a soldier-in-training," the base said.
The soldier's name is being withheld pending notification of next of kin.
"I ask for your patience and consideration for our fallen brother's extended family until the next-of-kin notification is complete and we are able to release his name," Beagle added.
Officials said the soldier's cause of death is under investigation.
The commander said "separate investigations" will take place to "determine the facts behind the incident and provided in time to our soldier's family, who rightly deserve this information."
Fort Jackson is home to the Army's main center for Basic Combat Training, often known as "boot camp." The base trains 50 percent of those soldiers in boot camp and more than 60 percent of women entering the Army every year, it says.