US authorities are investigating an incident involving hazardous materials at the Pentagon building, the Arlington County Fire Department said on social media, Reuters reported, quoted by BTA.
Earlier, CNN reported that several floors of the building had been evacuated and cordoned off.
Pentagon spokesman Sean Parnell confirmed that security systems "have detected an air quality issue requiring precautionary measures until the severity is determined".
"The Department (of War) is implementing standard protective protocols, including a shelter-in-place order in the affected area," Parnell said. He added that specialized teams are on site and ready to provide assistance to people in the building.