Over 50 Vietnamese girls were hospitalised after they fainted at school, and officials Saturday blamed the incident on an episode of "mass hysteria".
"This is the first time such a thing has happened here in the district," said Luong Thanh Nhan, a policeman in Vietnam's southern An Giang province. "It was not the food or the environment which caused the incident."
The director of the medical centre in Thoai Son district said the 51 girls who fainted suffered from "hysteria", reported the Thanh Nien newspaper. He added that the "syndrome is commonly found among young, sensitive school girls".
School and medical officials said the first girl to faint was brought to the Vong Dong Senior Secondary School's nurse on Thursday. The five girls that accompanied the 13-year-old to the nurse's office then fell unconscious.
Emergency medical personnel arrived to take the children to hospital. Dozens of students in their classrooms, who saw the girls being carried away, also suddenly collapsed.
Most of the girls were released from the medical centre on Thursday. But according to Nhan, four students remain in the hospital in stable condition.
"Everyone was so worried about the case," said Nhan. "We still don't know what the cause was."