A teenager who shot and killed his grandparents at their home before opening fire at a school in Thailand had been bullied and was 'stressed' by schoolwork, police have revealed. The 14-year-old shooter struck his grandparents, using his grandfather's handgun, before opening fire at a secondary school in Nonthaburi province, bordering Bangkok, killing five school staff.Some 30 more were injured at the school before the suspect turned the gun on himself. Purin Khumchoo, 17, said he was among the students who had nearly been shot, and described the gunman as 'troubled.''He was my junior, but I had a feeling that he was a troubled kid. My group of friends who knew him said he was interested in the FBI and guns, and that he was bullied by many other students,' Purin told AFP outside his school.'When I saw him aiming the gun at me, I thought he looked very professional, as if he had been trained for a long time.'The suspect was said to be an avid gamer, while a teacher at the school said that he was a 'good kid with good study records', and that he was not known to be aggressive.Those killed at the school were all teachers and staff. Nine of those who were wounded are in critical condition, Prime Minister Anutin Charnvirakul said.Newly emerged images now show the suspect, dressed in the school's purple uniform, stalking the building's corridors The images capturing the shooter were taken before he turned the gun on himself A pupil reunites with a relative after being evacuated from Debsirin Nonthaburi SchoolHe added that the teenage suspect was 'under stress' and had planned the assault.'Police interrogated his close friend, who said the suspect had been under stress' related to his schooling, Anutin told reporters outside the secondary school in Nonthaburi province, bordering Bangkok.'His actions also suggested that he had clearly planned (the shooting).'Newly emerged images now show the suspect, dressed in the school's purple uniform, stalking the building's corridors as he appears to load up a handgun.Pupils streamed out of the high school as the wounded were loaded onto ambulances and teachers hugged each other and cried. In photos circulated by emergency workers, one person is seen lying on a stretcher outside an ambulance, while a medic tends to another.Lieutenant Colonel Dechrapee Kongdee, the Nonthaburi provincial police commander, confirmed earlier that the ⁠suspected shooter had died. The gunman also allegedly killed his grandparents, whom he lived with, before going to the school. They were found dead at home, Thailand's public health minister said. A witness told reporters that pupils hid inside a classroom while they heard gunshots from another building before police officers knocked on the door and cleared a way for them to leave the building.The suspect was reportedly seen reloading ammunition inside the building, according to sources at the scene. Photos published by local media show the suspect wearing a purple school uniform and carrying a black cross-body bag, with several bullet casings visible on the ground. Armed response units were deployed to the school while pupils and staff were evacuated from the campus.One 18-year-old pupil told Reuters he initially thought firecrackers were going off.'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.'Emergency worker Kiatikhun Verapongpradith, 47, described arriving as the shooting was ongoing and his team treated pupils with injuries in the back, chest and arms.They found a male teacher lying dead on an upper floor of the school, and in another room they found a female teacher with wounds in her chest and arm.'We gave CPR for about 30 minutes and rushed her to the hospital as we could not get her heart rate up, but we tried our best,' he said.In the 2025 academic year, the school had an enrollment of around 3,100 pupils and 147 teachers, according to district authorities.