Two more gas stations were robbed at gunpoint in Suffolk Monday night, making it the fourth similar incident in the county since Friday night.

Police say two men wearing skeleton masks displayed handguns and demanded cash from a female employee at the BP Gas Station on Horseblock Road in Farmingville just before 10 p.m. Monday.

MORE: Police: Robbers hit 2 Medford stores within 2 days     

The female employee complied and the men took off on foot. The employee was not injured.

Police say the Shell gas station in St. James on Middle Country Road was robbed in a similar manner two hours later. Najrul Mohammed, who works at the Shell station, told News 12 that three men armed with a gun suddenly rushed the cashier.

Two other robberies occurred on Route 112 in Medford over the weekend.

Police have clear surveillance video from all four locations. However, they do not offer many clues since the suspects are completely covered up.

Authorities are reviewing the footage and other evidence to determine if the robberies are connected.

Authorities are urging anyone with information about the robberies to call Crime Stoppers at 1-800-220-TIPS.