High Carbon Monoxide Levels Sicken 70 Students at Chicago Elementary School

High levels of carbon monoxide sickened 70 students and 7 adults at a Chicago elementary school today, officials with the Chicago Fire Department said.

They were hospitalized and are all expected to be OK, according to ABC station WLS in Chicago.

Officials are still investigating what caused the CO levels, WLS said. The school, Prussing Elementary, was evacuated, said WLS.