PHILADELPHIA -- Prosecutors say no charges will be filed against a mobile phone store clerk who shot and killed an armed man during an alleged robbery attempt in southwest Philadelphia. The Philadelphia district attorney's office said last week that police deemed the shooting justifiable self-defense after reviewing surveillance video from the Metro PCS store.Police say a man entered the store shortly after 4 p.m. Monday and tried to hold it up. They say the store employee, who has a permit to carry a firearm, fired multiple times.The man was pronounced dead at the scene minutes later. Police were withholding his name pending notification of his familyMetro PCS, now known officially as Metro by T-Mobile, called it a "tragic situation" and said the company was cooperating with law enforcement.