By Jeremy Gorner, Chicago Tribune

A woman was seriously injured today from high levels of carbon monoxide in a South Loop high-rise, the Chicago Fire Department said this afternoon.

Around 11:45 a.m., more than 30 people were evacuated from the 10-story apartment building, located in the 1300 block of South Wabash Avenue, when the toxic, odorless and colorless gas spread through the building’s ventilation system.

A female tenant from the 7th floor was taken in serious condition to Mercy Hospital and Medical Center for smoke inhalation, fire department spokesman Larry Langford said. Five ambulances were sent to the scene as a precaution, but no other injuries were reported.

The source of the carbon monoxide was a gasoline-powered power-washing device in the basement, which was being operated “in a very confined space,” said Eve Rodriguez, a fire department spokeswoman.

Firefighters initially detected the readings coming from a stairwell between the basement and the first floor, she said. But at one point, there were high readings on every floor, according to Langford.

The evacuees have since been allowed to return to the building.