Pentagon lifts lockdown, says was due to false alarm

"Earlier this morning, Pentagon occupants were notified of a potential air quality issue, prompting immediate precautionary safety measures and evaluation. Subsequent testing confirmed no hazard exists, and normal operations have resumed," Pentagon spokesman Sean Parnell said in a statement.

The Arlington County Fire Department earlier said it had units "including our Hazardous Materials Team" operating at the Pentagon, which is the headquarters of the US Defense Department.

The fire department had described it as a "hazardous materials incident," while Parnell had announced a "shelter-in-place order for the affected area."