Pentagon officials ordered partial lockdowns and evacuations after a hazardous materials sensor system detected a possible air quality problem inside the building, according to sources familiar with the situation.
The alert prompted shelter in place orders for multiple floors and corridors, and response teams moved into affected areas while additional testing took place, Pentagon chief spokesperson Sean Parnell wrote on X that normal operations had resumed.
Sources told CNN that first responder radio traffic indicated the sensor had picked up a possible presence of anthrax, but one source familiar with the incident said the sensor system was malfunctioning and the alarm proved to be false.
Internal guidance sent by the Pentagon security team described an air quality issue and warned that additional testing could take one to two hours, and it noted that response personnel from multiple agencies were on site.
The Arlington County Fire Department dispatched units to support the Pentagon Force Protection Agency hazardous materials response team, Arlington County Fire Department spokesperson Capt. Jamie Jill said, and Arlington Fire & EMS posted that its Hazardous Materials Team was operating at the Pentagon during the incident.
Reportedly, floors two through five in corridors four through seven were locked down, and offices in the impacted area included the Navy’s main public affairs office and the Secretary of the Army’s office, one source told CNN.
One source said police inside the building wore gas masks and full chemical protective gear while hazmat teams conducted assessments and on-site testing.
Response Systems And Background On Detection
Pentagon officials said subsequent testing confirmed no hazard existed and praised first responders for swift actions, Parnell wrote when announcing a return to normal operations.
Fox News reported that a device had picked up a biohazard scent and that a hazardous materials team scrubbed several locations in the Pentagon’s A ring, according to a Pentagon official and a Pentagon source speaking to Fox News.
Experts described continuous air monitoring sampling as a method facilities use to look for spores and airborne threats, Jake Jordan of the Nuclear Threat Initiative said, and he noted laboratory confirmation for pathogens can require specialized handling.
Hayley Severance, formerly a senior Defense Department advisor on biological threat reduction and now with the Nuclear Threat Initiative, said there is a history of some false alarms with anthrax detection and emphasized the value of rapid precautionary responses.
The incident underscores the Pentagon’s built systems to detect and contain airborne hazards, which Fox News said include sensors, modeling and ventilation controls intended to isolate affected areas while responders assess potential threats.
