A horrifying school shooting outside Bangkok left at least eight people dead Friday after authorities say a 14-year-old boy killed his grandparents before storming his school and opening fire on teachers and students.

Five teachers were fatally shot during the Aug. 7 massacre at Debsirin Nonthaburi School in Nonthaburi province, just outside Thailand’s capital, according to officials.

The suspected teenage gunman also died, bringing the reported death toll to eight when his grandparents are included.

Authorities say the bloodshed began at the boy’s home, where he allegedly shot and killed his grandparents before heading to the school shortly after 10 a.m. local time.

Once on campus, the teenager allegedly moved through the school firing a 9mm handgun.

Students scrambled for their lives as gunfire erupted.

One eighth-grade girl told the BBC she had been standing near a teacher when the shooting began.

“I couldn’t see anything but a [cloud] of dust,” she said. “He walked from room to room.”

The student said her desk was very close to the teacher and that she eventually escaped by climbing over the school fence with friends.

A teacher at the school described the terrifying moment he realized something was terribly wrong.

“Then I saw pupils run out, screaming,” the 31-year-old teacher told the BBC. “I asked them what was going on. They said ‘there’s a shooting!’”

The tragedy quickly became personal for him.

One of the teachers killed, he said, had been his friend since they were students at the same school.

“She was my age,” he said. “We went to this school together as students. Then we both became teachers at this school.”

Emergency crews rushed to the scene as wounded students and staff were carried away for treatment.

Thailand’s Ministry of Health said 22 people were hospitalized following the shooting.

Earlier reports had put the number at 15, including two people in critical condition. Health Minister Pattana Promphat reportedly said as many as nine people may have suffered serious injuries.

Emergency worker Kiatikhun Verapongpradith, 47, told Reuters that students were among those shot, with responders treating injuries to the chest, back and arms.

Police said the teenager used a 9mm firearm believed to belong to a relative.

The BBC reported that the gun belonged to the boy’s grandfather and that authorities allegedly found the teenager carrying at least 34 additional rounds of ammunition.

Terrified students reportedly barricaded themselves inside classrooms as shots rang out from another school building.

Police later helped some of the students escape.

Authorities are now trying to piece together what drove the 14-year-old to carry out the attack.

Thailand’s deputy interior minister Polapee Suwanchawee said evidence gathered so far indicated that the teenager lived with his grandparents and was an avid gamer, according to the BBC. Officials have not established that gaming played any role in the shooting.

After the attack, the boy allegedly turned the gun on himself. He died while being transported to the hospital, according to the BBC.

Royal Thai Police spokesperson Trairong Piwpan confirmed the shooting took place at Debsirin Nonthaburi School in Nonthaburi province.

Thailand’s Ministry of Health offered its “deepest condolences to the families of the deceased and to all those injured in the incident.”

The shocking violence comes just months after another school shooting in Thailand.

In February, authorities said a 17-year-old stole a gun from police and opened fire at a public high school in southern Thailand, killing one person and injuring two others.

Friday’s massacre has now left another school community devastated — with five teachers dead, students recovering from gunshot wounds and investigators searching for answers about how a 14-year-old allegedly turned a family gun into the weapon behind a horrifying rampage.