BANG KRUAI, Thailand – When a shot rang out at the Debsirin Nonthaburi School on the outskirts of Bangkok on Friday morning, 14-year-old Khim and her classmates peered over a balcony to see if the noise had come from a construction site.

But more loud bangs followed, until a teacher ushered them all into a classroom, checked a messaging group and confirmed to the now terrified students: There was an active shooter in their building.

“I heard multiple gunshots and felt like we weren’t going to survive,” Khim, who asked to be only identified by her nickname, said Saturday, describing how her classmates moved desks to block a door, turned off the lights and huddled together near the classroom windows.