Details in each case vary slightly, but investigators believe these cases may be related.
The restaurants are scattered across the city including businesses on Broad Street, Broadway Avenue, Albert Street, and University Park Drive.
The robberies over the past few months usually occured in late evening.
The first of these incidents happened in mid-October of 2016, and the most-recent robbery — believed to part of the series — occurred as recently as December.
The similar circumstances happen typically past 11:00 p.m., a firearm and/or other weapons are used and there is generally money demanded.
Police to believe there may be a number of suspects involved.
The suspects then make off with the cash, apparently in vehicles.
To date, there have been no physical injuries to employees or business patrons; however there is great concern because of weapons involved.