Multiple floors of the Pentagon are placed on lockdown and some staff are evacuated after authorities respond to a reported “hazardous materials incident” at the U.S. military headquarters in Washington, D.C. Several outlets report that Arlington County Fire Department units, including a hazardous materials team, are operating at the site. A Pentagon spokesman, Sean Parnell, says the building’s “sophisticated systems” detect an air quality issue and that precautionary measures remain in effect until officials determine the significance of the readings. Authorities describe the response as consistent with standard safety protocols. These include a shelter-in-place order for the affected area while response teams assess conditions inside the building. Some reports also describe officers or personnel in chemical protective gear and restrictions affecting corridors and multiple levels. Overall, available accounts do not specify the exact substance involved or provide confirmed details about any injuries. The situation is framed as an investigation into potentially hazardous exposure or air-quality concerns, with safety procedures underway as personnel are protected and crews respond.