Multiple Pentagon floors locked down, evacuated due to ‘hazardous materials incident’

The Pentagon was locked down and partially evacuated on Thursday due to a false alarm by a hazardous materials sensor, two sources familiar told CNN.

Multiple floors and corridors inside the building had been locked down and others were evacuated due to a “hazardous materials incident,†three sources familiar and the local fire department said earlier on Thursday.

At 1:31pm Pentagon spokesman Sean Parnell posted on X that “normal operations have resumed†at the Pentagon.

“Earlier this morning, Pentagon occupants were notified of a potential air quality issue, prompting immediate precautionary safety measures and evaluation,†he wrote. “Subsequent testing confirmed no hazard exists.â€

The evacuation was triggered when a Pentagon sensor system detected the possible presence of anthrax, according to first responder radio traffic and a source familiar with the incident. But the sensor system was malfunctioning, one of the sources familiar said, causing the false alarm.

Parnell said earlier on Thursday that systems within the Pentagon had “detected an air quality issue necessitating precautionary measures until we determine its significance.â€

“The Department is executing standard protection protocols, including a shelter-in-place order for the affected area,†Parnell said. “Response teams are in place and ready to support building occupants.â€

Internal guidance sent by the Pentagon’s security team said an “air quality issue†had been detected and additional testing was needed.

“This additional testing could take one to two hours,†the message said. “Response teams are in place and ready to support building occupants if necessary. You may observe response personnel from multiple agencies and precautionary measures taking place in the center courtyard. Please do not interpret these activities.â€

Facilities such as the Pentagon might employ “continuous air monitoring sampling,†where systems processing large volumes of air look “for the presence of [anthrax] spores,†said Jake Jordan, who oversees biosecurity programs for the Nuclear Threat Initiative nonprofit.

While responding hazmat teams may be capable of rapid on-site testing, pathogens such as anthrax require specialized handling for confirmation laboratory tests.

The Arlington County Fire Department sent units to assist the Pentagon Force Protection Agency’s hazardous materials response team, according to fire department spokesperson Capt. Jamie Jill.

A post on social media from the Arlington Fire & EMS said Arlington County Fire Department Hazardous Materials Team were operating at the Pentagon “during a hazardous materials incident.â€

Floors two through five in corridors four through seven of the sprawling Pentagon complex were locked down, two of the sources said. Floors two through five are the above-ground floors of the Pentagon; there are nine corridors total in the building. Offices within the impacted area include the Navy’s main public affairs office and the Secretary of the Army’s office.

The third source told CNN that police in the building wore gas masks and full chemical protective gear.

Hayley Severance, who was a former senior advisor to the Defense Department on biological threat reduction before joining the Nuclear Threat Initiative, told CNN that “there is a history of … some false alarms†with anthrax detection, but ultimately “it’s really good that they’re taking these seriously, because … it deserves this type of rapid precautionary response.â€

This story has been updated with additional reporting.

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