Two students, ages 14 and 15, opened fire at San Jose National High School in Tacloban City, Philippines, killing three classmates and injuring at least 20 others.

Fifteen of the injuries were caused by gunshots, while others occurred as students fled the attack.

Police arrested both suspects, who reportedly told investigators they had been bullied at school.

Authorities said the teens used handguns that were brought onto campus despite limited security and recovered at least 40 shell casings from the scene, NBC News has reported.

President Ferdinand Marcos Jr. ordered a full investigation and called for increased security at schools and other public places.