A teacher was killed and four other people injured in a shooting at a school in Thailand, where the gunman took his own life, authorities say.

The incident took place in Debsirin Nonthaburi School in the Bang Kruai district on the northwestern outskirts of Bangkok. Police identified the perpetrator as a student. There were no further details provided.

In photos circulated by emergency workers, students streamed as ambulances operated at the site. In one photo, one person is seen lying on a stretcher outside an ambulance, while another is attended to by a medic.

One 18-year-old student told the Reuters news agency he initially thought there were firecrackers going off or someone banging an object.

“I didn’t think it was a gun at first,” he said, “There were many shots: bang bang bang. Then it went quiet. Then it started again.”

In February, a teacher was killed and a student injured in southern Thailand’s Hat Yai district after a gunman opened fire at a school.