The 35-year-old victim was uninjured.
Police are searching for the trio and are asking anyone with information to contact Crime Stoppers at 800-244-TIPS. All calls will remain confidential.
The armed robbery took place on Prince Street just before 10 p.m., police said.
The trio approached the man and one of the robbers, a man believed to be in his 20s who was wearing a black bandanna, black shorts and a black shirt, displayed a pistol and demanded the victim's wallet, police said.
The other two men were described only as wearing dark-colored clothing, police said.