Multiple floors of the Pentagon were evacuated Tuesday following the detection of a hazardous substance. CNN reported the incident, citing three anonymous sources familiar with the situation. Pentagon spokesperson Sean Parnell confirmed that building surveillance systems registered air quality concerns, prompting the evacuation. Fire crews are currently on site investigating the cause and mitigating the issue. The nature of the substance remains unknown at this time, and further details are limited. Authorities are working to determine the extent of the contamination and ensure the safety of personnel.