Pentagon Lockdown Ends After False Anthrax And Air-Quality Sensor Alarm In Arlington

The Pentagon in Arlington, Virginia was placed on lockdown for several hours on Thursday after internal systems detected a potential air-quality issue that later proved to be a false alarm, with subsequent testing confirming no hazard and normal operations resuming.

“Pentagon lifts lockdown after air quality scare proves to be false alarm The chief Pentagon spokesman said "normal operations have resumed”

ABC News

Pentagon spokesman Sean Parnell said the building’s systems had “detected an air quality issue necessitating precautionary measures until we determine its significance,” prompting “a shelter-in-place order for the affected area.”

ABC News

CNN reported the evacuation was triggered when a Pentagon sensor system detected the possible presence of anthrax, but the sensor system was malfunctioning, causing the false alarm.

The Arlington County Fire Department said its hazardous materials team was operating at the Pentagon “during a hazardous materials incident” in support of the Pentagon Force Protection Agency’s Hazmat Team.

Multiple outlets described the same corridor-level restrictions, with the Pentagon Force Protection Agency putting out an email to shelter in place in corridors 4,5,6 and 7 from floors 2-5, while other floors were evacuated.

Newsweek said the evacuation was triggered when a Pentagon sensor system detected the possible presence of anthrax, but “the sensor system was malfunctioning, one source told CNN, causing the false alarm.”

CBS News

CNN reported that “Floors two through five in corridors four through seven” were locked down, and it said police in the building wore gas masks and full chemical protective gear.

At 1:31 p.m., Pentagon spokesman Sean Parnell posted on X that “normal operations have resumed,” and the Pentagon’s shelter-in-place order had been active until all-clear was given.

The Pentagon’s internal guidance said additional testing was required to determine the cause of the alert and that it could take one to two hours, while response personnel from multiple agencies were expected in the center courtyard.

“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”

CNN

ABC News said the partial lockdown was lifted after no hazards were found, quoting Parnell that “normal operations have resumed,” and it described shelter-in-place earlier in response to a potential air hazard situation.

Time reported that Parnell wrote on X at 1:31 p.m. ET that precautionary safety measures had been lifted after determining the “hazardous materials incident” was a false alarm.

CNN quoted Jake Jordan, who oversees biosecurity programs for the Nuclear Threat Initiative nonprofit, saying facilities like the Pentagon might employ “continuous air monitoring sampling,” and it added that pathogens such as anthrax require specialized handling for confirmation laboratory tests.