Seven people, including four children, were killed and 18 others injured when a roof over a school sports field collapsed in a storm in Thailand, officials said Tuesday. 

The children, aged between six and 13, were playing in the open-sided building at a school in Phichit province on Monday, watched by a number of spectators. 

At about 6:30 p.m. (1130 GMT) the storm struck, according to local media, and heavy rain and high winds caused the roof to collapse suddenly.