Spoiled leftovers have been identified as the cause in a food poisoning case that hospitalized 42 kindergartners in east Zhejiang Province, local authorities said Monday.

The students at an unlicensed kindergarten in the Xiaoshan District of the provincial capital of Hangzhou suffered vomiting and diarrhea after eating lunch on July 8 and were rushed to the hospital.

After several days of medical tests and analysis of the lunch samples, and the children's vomit and excrement, local health authorities confirmed Monday that Staphylococcus aureus, a coccal bacterium, was found in the leftovers the children had eaten during lunch.

To date, 36 children have been discharged from the hospital. Six others remain under medical observation but in stable condition, a publicity official with the Xiaoshan District government said.