Authorities have launched an investigation after multiple students in a middle school in the Pudong New Area reported feeling sick.
Pudong police said they received a report on Tuesday afternoon that multiple students at the school on Xianan Road were feeling unwell.
An initial investigation indicated that two 13-year-old female students went back to the classroom during a PE class in the morning and mixed detergent and bleach into the cups of their classmates, according to a statement by the police.
All of the affected students were rushed to hospital and discharged that evening after treatment, police said, adding that they had all returned to the school.
They will further probe the incident together with the local educational department, the statement said.
