Two children have died in northern China after drinking yogurt allegedly tainted with rat poison by the owner of a rival kindergarten, media report.
The girls in Hebei province suffered convulsions and started foaming at the mouth after consuming the yogurt on 24 April, Xinhua news agency said.
The kindergarten owner is said to have confessed to the poisoning because two schools were competing for children.
A man who allegedly helped her plant the yogurt has also been detained.
According to Xinhua, the girl's grandmother found the yogurt along with several school notebooks on a roadside close to their school in the village of Lianghe, Pingshan county.
She took it home and gave it to the girls when they came back from school.
The head of a rival kindergarten is reported to have confessed to lacing the yogurt with rat poison because the two schools were both trying to attract children.
China has seen a string of shocking cases in recent years, many involving tainted food and medicine.
The BBC's Damian Grammaticas in Beijing says these have led to bouts of national soul-searching and questions about how profits are often put before people's health.
In the worst incident, five years ago, tens of thousands of children were sickened after drinking tainted baby milk powder.
The industrial chemical melamine had been added to the powder to make its protein content appear higher.
Six children died and two of those found responsible for the poisoning were given death sentences.