RALEIGH, N.C. — Raleigh and Cary police are working together to solve a rash of armed robberies at Triangle-area stores, mostly fast food restaurants. Authorities said the thieves are striking so frequently that they are starting to target some places twice.

Authorities said the robbers struck again at two restaurants in Raleigh Sunday night -- the Taco Bell on Capital Boulevard and the Subway on Six Forks Road. Police said the

Subway restaurant

was targeted for a second time. Investigators said they believe the pair is responsible for at least 16 robberies in the past two months.

Surveillance videos caught the armed robbers at the Quality Mart on Walnut Street on Thursday, their second robbery at the convenience store. Investigators said that in each of the incidents, the individuals have their faces covered and at least one of them is armed with a handgun.

"It's really a split-second away from turning into something much more serious any time a gun is involved," said Jim Sughrue, of the Raleigh Police Department. "It appears that they are going to keep committing crimes until they are caught."

Police said the robbers have been targeting two parts of Wake County repeatedly: Six Forks Road in Raleigh and Walnut Street in Cary.

Crimestoppers is offering a reward for any information leading to the arrests of the individuals. If you have any information about the case, you are asked to contact Raleigh police at 919-890-3555 or Cary police at 919-469-4017.