Why Is The Emergency Broadcast System Testing Itself For Two Hours Just Outside Of D.C.?

This is the eerie scene since 4 am this morning, this has been going on in Northern Virginia outside DC for 2 hours. The woman in the video says the buildings in view are secure government structures, so is the emergency broadcast test a glitch or is the government expecting something big to happen? Reports from Northern Texas say they are hearing the same test over and over again.