An investigation has determined what made 40 people sick and forced the cancellation of three days of classes at the Hinton Community School. Siouxland District Health Department Director Charles Cipperly says a Norwalk-like virus is to blame. It’s believed the virus was in food served to teachers and administrators during training prior to the first day of school.The teachers and administrators became sick on the first day of school last Thursday and classes were cancelled until Wednesday of this week. Cipperly says they don’t know if the virus was in food in the school cafeteria, or food brought in from a restaurant. They’re taking some preventative measures in the cafeteria, such as using rubber gloves and making people wash hands.Cipperly says all those affected were at the school training. There were no cases outside the school, but he says it can be hard to detect.Cipperly says the illness usually lasts for only one or two days. He says all the Hinton school personnel have recovered.