There have been seven such robberies in Raleigh since March, and two in the last three days. Investigators said they're targeting fast food restaurants across the city.
"There's a high probability that there is a pattern here and that the same suspects are responsible for more than one crime," said Jim Sughrue, a spokesperson for the Raleigh Police Department.
Sughrue also said there are similarities with an eighth armed robbery at a Burger King on Colondades Way on Oct. 2.
The latest robbery happened around 8:45 p.m. Monday at a Subway Restaurant on Six Forks Road in Raleigh. A worker at the Subway, who did not want to be identified, told WRAL that the gunman came through the door, ordered her to the ground and then stole all the money from the cash register.
"Any crime in which a gun is involved is a split second from turning into something much more serious," said Sughrue.
In five of the crimes, two male suspects were involved. Two males and a female committed the Aug. 29 Bojangles armed robbery, and only one suspect was seen at the Subway robbery on Monday.
The suspects' clothing descriptions have varied, but in each case the males wore hats pulled down low to hide their appearances. The police have surveillance video from some of the robberies, but the images have not helped to identify the suspects.
Anyone with information is asked to contact the Raleigh Police Department's Detective Division at
. A reward is offered to uninvolved parties for information that assists the investigation.