There are no classes today for students in the North Mac District in central Illinois. The cancellation comes after more than 130 people became ill on Monday.
The school day ended abruptly Monday morning at North Mac Intermediate in Girard. A faulty furnace flue resulted in a carbon monoxide leak, sending mostly middle school students and some adults to hospitals.
Several began feeling nauseous and dizzy, according to North Mac Superintendent Marica Cullen.
"All students were conscious, all students were coherent. We did call 911 and it was amazing to see the outpouring of support from other communities. Their volunteer fire-rescue rigs just flooded this building - and brought oxygen (which) was what those kids needed and they needed it immediately."
At least three students were admitted to the hospital. The rest were released.
The district says repairs to the furnace have been made, and the decision to call off school is precautionary.