Law enforcement would not say if he had a specific target or motive.
Passengers in the US are allowed to travel with unloaded firearms in a hard sided case as checked luggage. Ammunition can also be checked.
TSA rules are specific:
- The traveler must comply with local and state firearms laws.
- Firearms must be declared to the airline. There is a federal form that must be filled out.
- Firearms must be unloaded and locked in a hard-sided container. Only the passenger should have the means of unlocking the firearm.
- Ammunition may be in checked luggage.
- Ammunition must be in hard sided cases or securely boxed.