Students from a Humboldt Park elementary school were transported to area hospitals Wednesday morning after some of them developed skin irritations.
The Chicago Fire Department dispatched five ambulances to Daniel Cameron Elementary School, at 1234 N. Monticello Ave., after school officials called the Emergency Medical Services Plan 1 as a precaution.
All of the children are in "green" condition, which means they are not suffering from any life-threatening illness or injury.
"It wasn't clear if they were actually experiencing the same irritation or if it was more of a hysteria type of thing, which tends to happen with groups of kids," said the school's principal, Stephen Harden.
The school held a pep rally in the auditorium that involved spraying whipped cream, but officials said the cream wasn't the cause of the irritation.
Classes resumed after the children were transported. Firefighters found no evidence of any toxic chemicals in the building.