Spokane, WA – Carbon monoxide was discovered in Old City Hall on Thursday morning emanating from a malfunctioning boiler, the Spokane Fire Department said.

The building was evacuated quickly, and no one was hurt.

Just before 6 a.m., morning workers called 911 when they discovered an “unknown odor” coming from the basement of the building, located at 221 N. Howard St.

Firefighters found extreme levels of carbon monoxide in the basement, which they determined to be from a defective boiler, the department said.

The building was ventilated and workers were allowed to re-enter after repairs began on the boiler, the department said.

The fire department determined the incident to be accidental.