Dozens of middle-school children in the southern Illinois town of Girard were taken to hospitals on Monday with nausea and dizziness possibly brought on by a carbon monoxide leak from a furnace, the Chicago Sun-Times reported.
An employee who answered the phone at Girard City Hall - 25 miles south of the state capital, Springfield - confirmed that a number of students from North Mac Intermediate School were being treated, but had no other details.
The fire department, state police and school district could not immediately be reached and the local police declined to comment.
The students were conscious and talking as they were taken away from the school in ambulances, North Mac school superintendent Marica Cullen said, according to the Sun-Times.
The State-Journal Register in Springfield reported that about 90 students had been taken to hospitals after students and staff complained of nausea around 9 a.m.
The school was evacuated and students were sent home, to hospitals or to shelters in churches, the State Journal-Register reported.