When a gunshot rang out at Debsirin Nonthaburi School on the outskirts of Bangkok on Friday morning, 14-year-old Khim and her classmates leaned over a balcony, wondering whether the noise had come from a nearby construction site.

Then more shots rang out.

A teacher quickly ushered the students into a classroom, checked a messaging group and confirmed their worst fears: An active shooter was inside the school.

“I heard multiple gunshots and felt like we weren’t going to survive,” Khim, who asked to be identified only by her nickname, told Reuters on Saturday.

She described how her classmates pushed desks against the classroom door, switched off the lights and huddled near the windows as they waited in fear.

For roughly 40 minutes, the alleged gunman, another 14-year-old student, moved through the school, killing three teachers and two school officials before turning the gun on himself.

Nine people were killed and 23 others wounded in the attack, Thailand’s deadliest mass shooting since 2022. The violence has renewed debate over gun control in Thailand, one of Southeast Asia’s largest gun-owning nations.

The tragedy had actually begun hours earlier, when the alleged gunman shot and killed his grandparents at their home at dawn.

He then took a bus to the school, 18 kilometers (11 miles) away, where he pulled out a gun and started shooting just before 10:00 a.m. (3:00 a.m. GMT), police said.

Trapped inside their classroom in Building 5, Khim started checking messages on her tablet.

Her older sister wrote to say she was inside a classroom in Building 4 next door, just as their mother messaged to warn her about the shooter.

“I said I knew, and I told her, ‘Mom, don’t call me, because the ringtone might go off,’” Khim said.

On student chat groups, photographs of the alleged shooter began circulating as he stalked through the school, which has more than 3,000 students and nearly 150 teachers, according to data from last year.

“Then, I heard a bang that was extremely loud. It felt like it was right next to my ear,” Khim said, describing the terror that descended on the classroom as she realized the gunman was only a few doors down the corridor.

“I didn’t know if the shooter was shooting selectively. I didn’t know if he wanted to shoot the whole school.”

Not long after, Khim said, the teacher instructed the students to evacuate the classroom as police secured parts of the school. But by then, the shooter had moved to Building 4, where her sister was still hiding.

In the middle of her shift at a public hospital Friday morning, 52-year-old nurse Kwan received a panicked call from her older daughter, Khim’s sister, telling her about the shooting at their school.

Based on conversations in a student chat group that her older daughter had told her about, Kwan, who also asked to be identified by a nickname, said she believed the shooter was likely using a handgun.

Still on the phone, she asked her older daughter to count the shots, estimating that a handgun magazine would hold no more than 15 to 20 rounds.

“Count the shots to see if he’s out,” she told her.

Police said the alleged shooter had fired at least 26 bullets. Another 34 rounds were found in his possession.

“But it turned out the sound kept getting closer and closer, eventually reaching Building 4, the building my daughter was in,” Kwan told Reuters on Saturday.

Using another phone, she called an emergency hotline, where an operator told her that police, including a specialized unit, had arrived at the school.

“I told them, ‘Right now, I am on speakerphone with my child. He is on the second floor, clearing rooms one by one from the right side,’” Kwan said.

Without warning, the call with her daughter cut off.

Kwan said she started praying until her daughter called her back a few minutes later. She was unharmed.

Several hours later, the family was reunited at their home in suburban Bangkok, not far from the school.

“When we are together, we fight all the time,” Khim said of her older sister. “But seeing her this time, I’ve never loved her this much before.”