Charleston Church shooting: Active Shooter Threat Instructor Training Drill - Date match
Source: fletc.gov
Department of Homeland security was running a training course called "ASTITP - Active Shooter Threat Instructor Training Program" from 15th -19th June in Charleston:
https://www.fletc.gov/training-calendar
Charleston ASTITP - Active Shooter Threat Instructor Training Program C_ASTITP-501 06/15/2015 06/19/2015
Make of it what you will.
Hat tip: comment by Pope of Discordia on Jay's analysis
Source: fletc.gov
