According to police, the worker thought a man was stealing from the store, located at Chestnut and Broad streets. She confronted him, and the man left.
However, after 9 a.m., the man returned to the store, this time with a woman. The pair continued the altercation with the guard, which eventually made its way outside the store.
The woman handed the man a knife, and he slashed the 32-year-old worker in the face, back and hands.
The offenders fled, but the man was quickly apprehended by SEPTA police officers. The woman got away.
The female guard was taken to Thomas Jefferson University Hospital and is listed in stable condition.
This investigation is ongoing.