Best Buy sales manager Orvin Smith told The Augusta Chronicle that man was seen on surveillance cameras Friday putting a laptop under his jacket at the Augusta store.
When confronted, the man became irate, knocked down an employee, pulled a knife and ran toward the door. Outside were four Marines collecting toys for the service branch's "Toys For Tots" program.
Smith said the Marines stopped the man, but he stabbed one of them, Cpl. Phillip Duggan, in the back. The cut did not appear to be severe.
The suspect, whose name was not released, was held until police arrived. The Richmond County Sheriff's office said it is investigating.