High levels of carbon monoxide sickened students at a Chicago elementary school Friday, and at least six of them were taken to a nearby hospital for treatment, the city’s Fire Department said.
Authorities knew that something was wrong after an Ernst Prussing Elementary student passed out, said Larry Langford, a Fire Department spokesman.
In addition to the six hospitalized, at least three others also felt sick at the school, Langford said.
It was not immediately clear what caused the high carbon monoxide levels or how high they were.
A message on the school website said that “an environmental condition” discovered around 10:15 a.m. (11:15 a.m. ET) “required us to evacuate the school building.”
Overhead images from CNN affiliate WLS showed students sitting outside the building late Friday afternoon, some of them lined up on the pavement and several wearing Halloween costumes.
Those not taken to hospitals were moved to another elementary school that Prussing Elementary identified as “our nearest evacuation site.”
Langford said that a large mobile ventilation unit was set up at the school to get fresh air into the building.
Carbon monoxide is an odorless, colorless and potentially deadly gas produced when cars, small engines, stoves, furnaces and other devices burn fuel.
According to the Centers for Disease Control and Prevention, those with carbon monoxide poisoning often experience headaches, dizziness, weakness, upset stomachs, vomiting, chest pain and confusion. Some 20,000 Americans each year go to emergency rooms, 4,000 are admitted to hospitals and more than 400 die as a result, the agency states.