By Kocha Olarn, Sophie Tanno, Helen Regan, and Angie Puranasamriddhi, CNN

Bangkok (CNN) — A 12-year-old girl has been confirmed dead in a school shooting north of the Thai capital Bangkok on Friday, which also claimed the lives of five teachers and marked one of the country’s deadliest such incidents in recent years.

Her death brings the total toll from the attack to eight.

The 14-year-old suspect stormed the Debsirin Nonthaburi School, where he was also a student, on Friday morning local time, and went on a shooting rampage before turning the gun on himself. Police said he also killed his grandmother and grandfather in their home, where he also lived.

On Saturday, local authorities said a 12-year-old female student died from her injuries, becoming the first confirmed child to have been killed in the attack.

The high school released a statement as the news of her death was announced, expressing “deepest condolences and profound sorrow” over her passing.

On Friday, the school shared a heartfelt tribute on its website to the five staff members killed in the shooting, along with their portraits in black and white, saying their “goodness and virtue” and “spirit as teachers will remain in our memories forever.”

They were named as deputy head teacher Kittipong Somrat; math teacher Prapaporn Konsila; Thai language teacher Nantchanatporn Nakplang; guidance teacher Tiwaporn Wanich; and secretary Saifon Sirikitchakajorn.

Nantchanatporn, previously a student at the school, was described as a “much-loved” teacher who dedicated her life “completely” to the school, according to local media reports. Just two days before the attack, Tiwaporn was recognized with a certificate as an outstanding teacher, Bangkok-based news outlet Khaosod English reported.

Thailand’s Prime Minister Anutin Charnvirakul said the attack could have been much worse if the suspected gunman had continued his attack, since he had more than 30 rounds of ammunition remaining.

Regarding a possible motive, the prime minister said the suspect had been experiencing stress related to his studies.

The boy’s father, who CNN is not naming until the authorities identify his son, later told CNN he had no idea why the boy carried out the attack and that he had a “good school result.” He told CNN his son is “guilty” but he doesn’t know why the boy allegedly carried out the attack.

During the rampage, terrified students huddled together under their desks, sobbing as gunshots rang out nearby, video filmed inside a classroom and verified by CNN showed. Further video showed students running out of the school as a staff member helped them evacuate.

“I heard multiple gunshots and felt like we weren’t going to survive,” 14-year-old student Khim told the Reuters news agency.

Hiding in her classroom with the lights switched off, Khim described the terror as she realized the shooter was just a few doors down the corridor.

She checked her tablet and saw a message from her sister, in the classroom next door, just as their mother messaged to warn about the incident.

“I said I knew, and I told her ‘Mom, don’t call me because the ringtone might go off. Then I heard a bang that was extremely loud… I didn’t know if the shooter was shooting selectively. I didn’t know if he wanted to shoot the whole school.”

An unnamed rescue worker told Reuters that “it was total chaos” when they arrived at the scene, where they administered first aid to students who had wounds to their back, chest, and arms.

Shooting spree

Using what police said was his grandfather’s handgun, the suspect opened fire at the well-known secondary school of about 3,000 students, located on a busy highway in the Bang Kruai district of Nonthaburi province.

Anutin told reporters that the gunman died after turning the weapon on himself. The suspect was left in a critical condition, with doctors providing emergency treatment.

Another student said he first heard what he thought was someone shooting at birds during his English class. Shortly after, another child ran in to inform them of the shooting.

The class immediately scrambled to barricade the room, pushing tables and chairs against the door and turning off the lights. Looking out of the classroom window, the student said he saw the shooter carrying a gun and walking to the building where his class was located.

Those inside the room crouched down on the floor in the darkness, waiting for help for 30 minutes. “Luckily, no one in our classroom was injured. The shooter only walked past our classroom,” he said, according to Khaosod English.

Concerned parents rushed to the school as news of the shooting spread.

The son of CNN’s senior travel producer Karla Cripps attends the school but was overseas at the time of the shooting, which began at about 10 a.m. local time.

“My son called me from Japan in a panic, telling me that he’d heard there was a shooting at his school. The kids were told to lock down in their classrooms, and he obviously was very upset,” Cripps said from outside the school.

Cripps said there was a “really sad atmosphere” at the school as ambulances streamed in and out, and parents comforted their children.

“My son heard his friend’s brother is in the hospital right now. He’s among the injured… It’s been terrible for everyone.”

Prior to carrying out the attack, the suspect had searched for and viewed websites related to mass shootings, police said. Authorities have seized nine computers or electronic devices from the suspect’s residence as part of their investigation.

The UN children’s agency (UNICEF) said the young age of the suspect raises “difficult questions” for society as it called for better mental health services for children in the wake of the attack.

Thailand’s Deputy Prime Minister Yodchanan Wongsawat said Friday a new mental health action plan to support teachers and students would be announced following the shooting.

Meanwhile, Thailand’s Ministry of Education pledged tighter security measures at schools, particularly measures to prevent weapons and other dangerous items from being taken onto school premises, along with a compensation scheme for those impacted.

Gun ownership in Thailand is high, compared with other countries in Southeast Asia. There were more than 10.3 million civilian-owned firearms in Thailand, or around 15 guns for every 100 people, according to 2017 data from the Switzerland-based Small Arms Survey (SAS).

Gun ownership is legal in Thailand with a license, although a person must fit certain criteria, including being at least 20 years old and not having a serious criminal record.