The Pentagon was placed on lockdown Tuesday morning after a report of a hazardous materials incident. Officials reported detecting the substance during routine security screenings. Emergency responders were dispatched to investigate, and a perimeter was established around the building. The lockdown affected the Pentagon Reservation, including the Pentagon itself, but has since been lifted. Authorities have not yet disclosed the nature of the hazardous material or the source of the incident, but stated there were no injuries reported. An investigation is underway to determine the cause and assess any potential risks.