An anonymous tip led military authorities to three of five stolen guns, which were discovered missing from Camp Shelby this week.
Some members of the 155th Combat Brigade were detained while the investigation went forward.
"One individual has been detained and if it's determined that he is responsible, he will be prosecuted. The thing we couldn't do was start to release soldiers. That way, if you released everybody, but two or three people are left then those two or three individuals automatically understand they are suspects," said 155th commander, Col. Augustus Collins.
The identity of the soldier was initially being withheld.