The incident was reported at 4:16 a.m., almost two hours after the robbery took place, reports state. No arrests have been made, and neither victim was injured during the robbery.
Jane Cousins, spokeswoman for the Chapel Hill Police Department, said the robber walked past the victims and then turned around.
One of the victims, a female UNC senior, said the man didn't seem suspicious.
"He seemed very nice," she said. "He walked about 30 feet past us, and then he turned around. I don't even know if I noticed him turn around and start walking toward us again."
But the victim said that when the man approached her, she felt uneasy because he had his hand in his pocket. He sat down next to the victims and pulled out a gun.
"He wasn't smiling this time, and he had this blank stare," she said. "He placed the gun down by the ledge to where someone driving by wouldn't be able to see it. He said, 'This is serious.'"
The other victim involved in the incident, a male UNC senior, said that at that point the man demanded money. "All I had was my ID and a check card," he said. "I put those things down and let him know that I didn't have any money."
The female victim said her friend told the man that neither person had money as she tried to push her purse behind the ledge.
"At that point the guy had gotten up, and he started walking away when he heard my purse fall," she said. "He told me to get down and get it. So I picked it up, opened it and gave him all my cash."