Phasid Trutassanawin was born on 21 September 2009 in Thailand. At the time of the shooting, he was 14 years old and enrolled in a private alternative secondary school located near Siam Paragon Mall in central Bangkok. He was studying toward IGCSE qualifications and lived with his family.

According to police and school officials, Phasid struggled academically and socially. Reports indicated that he was frequently bullied at school and experienced significant pressure from his parents regarding his academic performance. In response to this pressure, he reportedly sent videos to his parents showing himself firing weapons at shooting ranges.

Phasid had previously received treatment for a mental health condition at Rajavithi Hospital. Authorities confirmed that he had recently stopped taking prescribed medication prior to the attack. Police stated that, at the time of arrest, he appeared confused and disoriented and was deemed medically unfit for immediate interrogation.

In the months before the shooting, Phasid obtained a modified blank pistol, illegally altered to fire live rounds. Phone records later showed he had been in contact with individuals suspected of supplying him with the weapon and ammunition.

On 3 October 2023, at approximately 4:10 p.m. local time, Phasid Trutassanawin carried out a mass shooting at Siam Paragon Mall, one of Bangkok’s most prominent shopping centers. Earlier that afternoon, at around 3:35 p.m., he arrived at Siam BTS Station and entered the mall shortly afterward. He was seen entering a restroom on the ground floor at approximately 3:42 p.m., where investigators believe he prepared his weapon.

At around 4:10 p.m., Phasid opened fire inside the mall using a modified blank pistol capable of firing live ammunition. He discharged 40 or more rounds, with at least 11 bullets striking people. Panic spread throughout the mall as shoppers and employees fled or hid inside stores. Police and mall security began evacuating the premises at approximately 4:45 p.m., while emergency responders worked to secure the area.

Among the victims were Zhao Jinnan, a 34‑year‑old Chinese tourist, and Moe Myint, a 31‑year‑old Burmese employee at a toy store, who was fatally wounded when a bullet pierced her heart and lung. Five others were injured, including citizens of China, Laos, and Thailand. One of the injured victims, Penpiwan Mitthampitak, a 30‑year‑old Thai woman who sustained multiple gunshot wounds to the head and torso, later died on 13 October 2023, bringing the total death toll to three.

Phasid fled the mall during the chaos and was located on the third floor of the Siam Kempinski Hotel, adjacent to the mall. Having run out of ammunition, he surrendered without resistance and was arrested by police at approximately 5:10 p.m. Images from the arrest showed him wearing glasses, a dark shirt, khaki cargo pants, and a baseball cap. He was carrying additional ammunition at the time of arrest.

On 4 October 2023, Phasid was formally charged with six criminal offenses, including premeditated murder, attempted murder, illegal possession of a firearm, carrying a firearm in a public place without permission, and discharging a firearm in public. Due to his age and mental state, proceedings were conducted under Thailand’s juvenile justice system. Medical professionals determined that he was not in a condition to be interrogated immediately following his arrest.

Police investigations led to the arrest of three adult suspects accused of selling the firearm and ammunition to Phasid. Raids conducted in Bangkok and Yala Province uncovered multiple blank guns, hundreds of blank rounds, and gun barrels. Phasid was subsequently transferred to a juvenile detention center, where he remains under custody pending further legal and psychiatric evaluation.

The shooting prompted the temporary closure of Siam Paragon Mall and Siam BTS Station, with parts of the transit system shut down during the emergency response. The station reopened less than an hour later, though evacuation efforts were complicated by rush-hour traffic and heavy rain.

Thailand’s Prime Minister Srettha Thavisin expressed condolences to the victims and issued a formal apology to Chinese authorities for the deaths of Chinese nationals. The suspect’s family released a public apology on 6 October 2023, accepting responsibility and pledging cooperation with investigators.

The incident reignited national debate over gun access, mental health treatment, and juvenile justice in Thailand. Despite heightened concern, authorities emphasized that such indiscriminate mass shootings remain rare in the country.