Philadelphia police say a security guard at a cell phone store fatally shot a man who was armed with a knife Tuesday afternoon.

The incident occurred inside My Phillie Wireless on the 2700 block of North Broad Street around 12:30 p.m.

According to police, a man armed with a butcher knife ran behind the store's counter. At that time, investigators say an on-duty security guard inside the store discharged his firearm, striking the other man once in the chest.

The man was rushed to Temple University Hospital by responding officers and was pronounced dead just after 1:30 p.m.

The investigation is ongoing.