According to two cashiers in the store, which is at Washington and Court streets in Newark, one suspect was armed with a gun and wearing a mask while the other appeared to be the lookout.
At the same time, a Newark police officer came into the store and shot the suspect who was armed in the chest. He arrested the second suspect.
The suspect who was shot was taken to University Hospital. He is in critical condition.
The officer, who was on duty at the time, was not injured.
The Essex County Prosecutor's Office is investigating a shooting incident.