Two people were killed in a violent act at Bangkok's Siam Paragon shopping center. Four others were injured, including a foreigner.
The suspect, a 14-year-old, was arrested after surrendering to police. The young suspect was armed with a gun.
Prime Minister Srettha Thavisin confirmed that the situation was under control at the shopping center, which is a popular spot for both locals and tourists.
An earlier report had indicated three casualties, but was later corrected by emergency services.
A spokesperson for the center focused on the prompt response from police and the security team, and thanked volunteers and employees. The suspect was taken to Pathumwan police station.
People on social media reported seeing shoppers quickly leaving the center, which was immediately closed. The nearby Siam metro station was also closed.
Videos from inside the mall show the chaos after gunshots were heard, and people taking shelter in stores and bathrooms. An ice cream vendor described his experience to BBC.
Siam Paragon is a popular destination in Asia, and this violent incident is a heavy blow to its reputation.
While gun ownership in Thailand is common, mass shootings are relatively rare. Last year, there were two notable incidents: one involved an ex-lawman who killed at least 37 people at a daycare, and another involved a soldier who shot and killed 29 people in Nakhon Ratchasima city.