BULACAN (Philippines)— As an alarm reverberated throughout a Philippine high school today, students scrambled behind locked doors and police swept corridors in a drill aimed at preparing for an attack once unthinkable in the Southeast Asian country.

About 3,000 junior and senior high school students at Carlos F. Gonzales High School north of Manila barricaded their classroom doors with tables and chairs, drew curtains and switched off the lights before crouching under tables to protect themselves.

The nationwide drills are part of a broader push by the Department of Education to strengthen security following two rare school shooting incidents that shook the Philippines in the past months.

In the disaster-prone country, where schools regularly conduct exercises for earthquakes and fires, active shooting drills are something new.

“We have already almost perfected our fire and earthquake drills, and this is something new, so we need to do this kind of exercise,” Education Undersecretary Malcolm Garma told reporters.

“Through this kind of exercise, we want our schools... to be aware, to be able to recognize these kinds of threats and to be able to respond.”