The Pentagon was locked down, and floors two through five were evacuated due to a false hazardous materials alarm, CNN reported on Thursday.
Multiple Arlington County Fire Department units, including their Hazmat Team, responded to a "hazardous materials incident" at the Pentagon, the department announced earlier on Thursday afternoon.
A Pentagon spokesperson said that authorities are working to evacuate employees due to an air quality issue.
"The Pentagon has sophisticated systems to ensure the safety of the building and its occupants. Those systems have detected an air quality issue necessitating precautionary measures until we determine its significance," Pentagon spokesman Sean Parnell said in an email.
"The Department is executing standard protection protocols, including a shelter-in-place order for the affected area. Response teams are in place and ready to support building occupants," he added.