A kindergarten teacher in Jiaozuo, Central China's Henan province, was arrested Monday after 23 children were hospitalized following an alleged poisoning. According to local media, the teacher, whose details were not revealed, poisoned the children's porridge with nitrite.

Several parents said the children at Jiaozuo's Mengmeng kindergarten were hospitalized after they started vomiting and fainting. Some of them were discharged after treatment but one was said to be in serious condition.

One parent told local media that his child was rushed to a hospital where doctors pumped the child's stomach. The parent, surnamed Hu, said the child was diagnosed with "poisoning by nitrite." Seven others remained in hospital for observation.

"The vomit was all over (my child's) pants. There were other children who were also throwing up, and they looked pale," one parent, whose last name was Li, reportedly said.

According to the U.S. Centers for Disease Control and Prevention, nitrite is likely a carcinogen used in fertilizers, food preservation and even munitions and explosives. High amounts, if consumed, can lead to increased heart rates, headaches, vomiting and even death.

According to state-run Global Times newspaper, the children ate certain porridge, which was supposed to taste sweet. "But the children said the porridge tasted salty," one parent said.

An investigation found that a teacher in the kindergarten put nitrite in the children's porridge that day, which led to the children's illness.

Employees at the Jiaozuo's education bureau were investigating the case and already sent the children to other kindergartens.

In an incident in March, 36 primary school students in southwest China's Sichuan province were hospitalized after eating some "mouldy food." The incident sparked a protest and reportedly led to the dismissal of the school principal. The incident raised concerns about food safety in schools.

This is a representational image of a classroom in Seifhennersdorf, Germany, May 14, 2014. Getty Images/Sean Gallup