According to preliminary investigation by the police, the incident occurred when seven children were playing in a large pit dug at the back of a house for the purpose of building a toilet.
Another boy, who was watching his friends from the ground level, found an insect which was crawling up a hay stack kept close to the pit.
Apprehending that the insect might harm his friends, he set fire to the hay stack to kill the insect. However, the burning hay got loose and fell on the playing children, the sources said.
A villager brought out three boys from the pit but the condition of one of them was critical, the sources said adding he was shifted to Nongpoh Civil Hospital.
The deceased children were identified as Wanbha Jynthem (8), Herbest Jynthem, (7), Sophika Jynthem (7) and Gulabsha Jynthem (5).
The nine-year-old boy who had lit the fire fled after the incident, the sources said.