In Tianshui City, Gansu Province, China, more than 200 kindergarten children have been hospitalized after school kitchen staff used lead paint as food coloring, per Chinese state media network CCTV News. The principal and seven other people have been arrested “on suspicion of producing toxic and harmful food.”

Of the 251 students enrolled in the private kindergarten, 233 were found to have abnormal blood lead levels (BLL), 201 of whom were hospitalized. According to CNN, some kids were taken to a different, larger city, Xi’an, for treatment, 70 of whom had BLLs that classified them for lead poisoning. Additionally, six of the children tested in Xi’an had BLLs over 450 micrograms per liter (μg/L), which is considered severe lead poisoning.

Investigators discovered that two food items served at the school—a red date steamed breakfast cake and a sausage corn roll—were found to contain lead at concentrations over 1,000 milligrams per kilogram (mg/kg), exceeding national limits for lead in food (0.5 mg/kg) by more than 2,000 times.

Kitchen staff are suspected of using lead paint labeled as “non-edible” to color the food items, possibly due to pressures from a financer of the school who wanted attract more enrollment by offering colorful food, per Tianshui City law enforcement.

Some aspects of the case suggest that the poisoning may have been chronic.