On Thursday night, just after 11:00 p.m., two of the suspects, one armed with a gun, walked into Stacy's Pizza on the 4200 block of Market Street.
Police say the suspects went in to rob the place, their third robbery in little over and hour.
In each case, a lone female employee was working the cash register.
Another robbery took place at Gold Star Pizza.
"He asked for menu items and at some point has a conversation and threatens to kill her - the employee," said Lt. John Walker, Southwest Detectives.
Police say the bandits began their crime spree on Saturday with their two female accomplices.
They allegedly robbed a Subway at 56th and Lancaster and the Hibachi Grill in Pennrose Plaza.
Detectives say each night, a stolen vehicle was used to commit the robberies then ditched.
"We believe they are going into these businesses, checking them out, then coming back when people are by themselves. It's usually late at night when these businesses are getting ready to close or there are not many people in these businesses," said Lt. Walker.
Police say they arrested the two females, 19-year-old Reyshawn Cherry and 18-year-old Alaya Tyler.
The two allegedly tried to act like they were witnesses to the crimes until police checked the surveillance footage. Investigators say they are not cooperating.
The two male suspects remain at large.
"The video surveillance is very good and we know people know these individuals. As they begin to continue their number of robberies and their aggressiveness, we need people to come forward and get them off the street," said Lt. Walker.
Anyone with information is urged to contact Philadelphia Police at 215-686-TIPS (8477), text a tip to PPD TIP (773847) or through PhillyPolice.com.