Children aged six to 13 went to the activity center at Wat Nern Por Primary School in Phichit Province to take shelter from the rain, in accordance with Facebook posts by the official disaster prevention department and public relations office of Phichit Province. (185 miles) north of Bangkok.
According to local media, a storm broke out around 6:30 p.m. local time, and heavy rain and robust winds caused the roof to suddenly collapse.
The regional public relations office said the fatally injured adults included two parents and a janitor, adding that 18 people were injured.
“In the blink of an eye, I heard a sound just like in a war zone, and within five seconds the storm reached me,” a witness told ThaiPBS.
“All the homes were destroyed by the storm, but this arena has completely collapsed,” local mayor Kannika Intarakul told the broadcaster.
Schools in Thailand often have open-top sports fields to guard children from the tough tropical sun while playing.
A six-year-old boy was taken to hospital but died from his injuries.
The injured were hospitalized in two hospitals for treatment. None of them were reported to be in serious condition.
The incident comes as Thailand enters the monsoon season, with heavy rain forecast across much of the country in the approaching days.
The meteorological department issued a warning for heavy rainfall in upper Thailand this week. Monday was also the official start of the rainy season.
Safety and maintenance standards in Thailand are sometimes lax, and constructing collapses usually are not unusual.
Neighboring Myanmar was recently hit by Cyclone Mocha, which tore through Rakhine State, killing 145 people.
Additional reporting by the Associated Press
