( CNN ) -- Dozens of Mexican schoolchildren were hospitalized after apparently falling ill from a meal at their kindergarten . At least 38 children ages four and five became sick after lunch at a state-run school in San Luis Rio Colorado , which sits right on the border across from Yuma , Arizona , emergency dispatcher Carlos Ibarra said . A local clinic alerted emergency officials Friday when 15 children suddenly showed up at their facilities with similar symptoms -- vomiting , diarrhea and fever , Ibarra said . The number more than doubled before the day was over . The children had eaten chicken salad and homemade agua de horchata . a refreshing rice water drink . Officials suspect the horchata was responsible for the food poisoning , Ibarra said . Some of the children were released from the hospital on Friday night . The food was prepared by the sister of one of the teachers who had been contracted by the school , Ibarra said . The school , named Manuel Cervantes Imaz , has a total of 312 students . The health department will conduct an investigation , he said .
A drink is suspected of having sickened 38 kindergartners in Mexico . The affected children live in the border town of San Luis Rio Colorado .