The Pentagon was placed under lockdown Thursday after building safety systems detected a potential air-quality threat, prompting officials to order workers in the affected area to shelter in place while emergency crews investigated the situation.

Emergency responders from Arlington County Fire and EMS were dispatched to the military headquarters after what authorities described as a hazardous materials incident. The agency announced the response in a message posted on X.

“ACFD units, including our Hazardous Materials Team, are currently operating at the Pentagon in support of PFPA’s Hazmat Team during a hazardous materials incident,” it said.

According to Pentagon spokesman Sean Parnell, the alert was triggered after internal monitoring systems identified an issue involving the building’s air quality, leading officials to take precautionary action.

“The Pentagon has sophisticated systems to ensure the safety of the building and its occupants,” Parnell said. “Those systems have detected an air quality issue necessitating precautionary measures until we determine its significance.”

He emphasized that established emergency procedures were immediately activated while authorities worked to determine the source and severity of the concern.

“The Department is executing standard protection protocols, including a shelter-in-place order for the affected area. Response teams are in place and ready to support building occupants,” he added.

The Pentagon, regarded as one of the most heavily protected government facilities in the United States, is equipped with extensive safeguards designed to identify airborne threats and prevent contaminants from spreading throughout the structure.

Its distinctive five-sided layout, consisting of multiple concentric rings connected by hallways, enables officials to isolate specific sections of the building while allowing the remainder of the facility to continue operating. This design helps protect the approximately 26,000 people who work there without requiring a full evacuation.

As investigators seek to determine what caused Thursday’s alert, attention has turned to the Pentagon’s advanced detection and containment infrastructure, known as Pentagon Shield, which was developed over many years.

The Pentagon Shield initiative was created in the aftermath of the September 11 terrorist attacks as part of a broader effort to defend the nation’s largest government office complex against chemical, biological, and radiological dangers.

According to publicly available technical documents, the system relies on an extensive network of sensors combined with computer-based modeling technology to identify potentially dangerous airborne substances and monitor their movement throughout the building.

“Building ventilation systems can be adjusted in real time to minimize air infiltration,” researchers wrote in a 2007 overview of the program.

Should a hazardous material be detected, officials can rapidly modify airflow patterns, seal off specific areas, and restrict the movement of air between corridors, reducing the likelihood that contaminants spread beyond the affected zone while emergency personnel assess the threat.

{Matzav.com}