It happened at the store on Bethlehem Pike in Montgomery Township.
One of the workers, Courtney Blackburn, said it happened while she was walking out to her car at closing time on Monday.
That's when she encountered a woman with a knife.
That suspect grabbed one of Blackburn's co-worker from behind forced both victims back into the store to get to the safe.
"I went to call 911 and she saw me go for my phone, and yelled 'drop it, drop it or I'll kill both of you," Blackburn said. "She definitely had a knife when she grabbed my co-worker. My co-worker has a cut on her face," Blackburn said.
The workers believe the robber had an accomplice because they heard another voice inside the store.
But at that point, the robber had covered the women's faces with t-shirts and tied them up.
No arrests have been made.