The incident happened at the Hempstead Turnpike location in East Meadow around 10:30 p.m.
According to detectives, the 42-year-old victim was loading packages into her vehicle when she was confronted by a man who demanded her pocketbook.
After she complied, the suspect stabbed her in the left forearm with an unknown object before fleeing the scene with the purse, which contained her cell phone and unknown amount of cash.
The subject fled in an unknown red vehicle.
The victim was transported to an area hospital by police ambulance where she was treated for a non-life threatening injury.
Detectives request anyone with information regarding this crime to contact Nassau County Crime Stoppers at 1-800-244-TIPS. All callers will remain anonymous.