West Whiteland Township Police say the incident happened on Saturday at the store at 103 N. Pottstown Pike.
Investigators say the four suspects entered the store and started stealing merchandise.
An employee of the store followed the women outside and tried to use his cell phone to take their pictures.
One of the women then grabbed the cell phone from the employee's hand. They got into a scuffle and the worker was punched and hit with pepper spray, police said.
However, the employee was able to grab a bag with some of the stolen merchandise. He took it back into the store, police said, as two of the women followed him.
The women punched the worker and put him in a headlock, but were not able to get the bag back.
All four then fled in a white Ford Focus.
The next day, police arrested 18-year-old Shanelle Davis at her home in Philadelphia and recovered the car.
A second suspect, 18-year-old Nirrah Jones of Philadelphia, later turned herself in and, police said, turned over the 7-Eleven worker's cell phone.
The final two suspects, 19-year-old Asia Henderson, of Philadelphia, and 22-year-old Najia Davis of Philadelphia, have also been arrested. They were at large when police issued a news release on Monday, but turned themselves amid coverage of the story.