Private security from an unidentified company got lost with an illegal unregistered firearm and 500 rounds. Makes sense.
You should read the article before you post. It names the security company, and explicitly says that he was licenced in VA. His only mistake was bringing it into DC where all guns have to be registered with the police.
Regarding the 500 rounds, I don't own a gun, but from what I understand (from before this incident) there are often shortages on certain types of Ammo, so people who go shooting regularly like to buy in bulk.