Deputies released surveillance pictures from the bank. The men have on hats and their faces are covered, but they were wearing distinctive T-shirts.
Investigators said they also wanted to talk to a man who they called a person of interest who was in the bank July 17.
The man wearing a white shirt with long hair was acting suspiciously, according to deputies.
Anyone with information is asked to contact Det. Raymond Yeager of the Sampson County Sheriff's Office at (910) 592-4141 or Chief Frankie Harrell of the Newton Grove Police Department at (910) 594-0829.
The NC Bankers Association is offering a reward up to $5,000 for information leading to an arrest and conviction.