Visitors attend an open day to celebrate National Security Education Day at the Hong Kong Police College in Hong Kong, China

national security day nsd event national security event chinese national security police training day counter terrorism training counter terrorism event visitors attending police education day hong kong police chinese police propolice event prochina government government supporters chinese visitors chinese attendees attendees supporters hongkongers series academy traning children exposed weapons children exposed violence weapons ammunition fake weapons fake ammunition dangerous hazard holding weapon china patriotism hong kong social issues violence exposed generational violence destruction students exercise celebration open day open to public watchers patrotism patriotic exercise grandstand sitting seats stadium show