Two kindergarten kids from Hebei Province were poisoned to death after drinking a bottle of yogurt that appears to have been deliberately tainted with rat poison by the jealous head of a rival kindergarten, local police confirmed with the Global Times on Thursday.

The two girls, aged five and six, ate the yogurt on the morning of April 24 in Lianghe village of Pingshan county. One of the girls died on the way to hospital and the other passed away Wednesday afternoon.

The yogurt was picked up on the roadside by their grandmother, Ren Shuting, along with a notebook and a pen in a plastic bag as she was taking the girls to the Lianghe Central Kindergarten in the village.

The grandmother gave the yogurt to the girls after they returned home in the afternoon.

Shortly after, both were found foaming at the mouth and in convulsions.

Ren has also been hospitalized for a few days for showing symptoms of poisoning.

A preliminary probe found that the yogurt was tainted with rat poison. According to the police, the head of a rival kindergarten confessed that she injected the poison into the yogurt, and asked a man to place it, along with school supplies, along the road to Lianghe kindergarten.

Police from Pingshan county told the Global Times Thursday that 39-year-old Shi Haixia, head of the rival kindergarten, was the lead suspect in the case and Yang Wenming, 51, had helped her plan the poisoning.

The police did not reveal the name of the rival kindergarten but said Shi was jealous that the Lianghe kindergarten had attracted more students.

Both Shi and Yang have been detained.

"The community is appalled," a resident from the village told the Global Times. "Local kindergartens have started to take precautions and warned parents not to bring food to school."

This is the worst in a series of such horrors in China in which kindergarteners have been the victims of violence.

A teacher from Yanjiao Youyou Kindergarten in Hebei Province was reported in March to have forced her pupils to drink urine as a punishment for not behaving well.

Yan Yanhong, a 20-year-old kindergarten teacher from Wenling, Zhejiang Province, was seen in several photos posted online showing herself brutally picking up a 5-year-old boy by his ears "for fun" and taping shut mouths of some children.

An Lijuan, an expert in preschool education, told the Global Times on Thursday that a majority of China's kindergartens are privately owned and often go unsupervised.

"It has put underage children in a vulnerable position as many tend to unleash their dissatisfaction and frustration with society on the children."