Officials started taking the fourth, fifth and sixth graders of the Wat Nong Ket Yai School to the Bang Lamung Hospital at 5.30pm.
Nopawan Khonsue, director of the school, said the pupils had a soup and spicy-and-sour boiled eggs for lunch. Almost 100 of them fell sick, suffering from vomiting and diarrhoea in the afternoon. The school later sought help from district officials as the pupils remained in a serious condition, she added.