Certain areas in the Pentagon went on lockdown Thursday morning due to an "air quality incident" that was later revealed to be a false alarm.
An alert, shared with Fox News Digital, carrying a "severe" rating was sent to employees in multiple corridors of the building directing them to shelter in place. All other personnel were told to avoid the area. As of 1:30 p.m. Eastern Time Thursday, the lockdown order was lifted, according to Pentagon officials.
"Earlier this morning, Pentagon occupants were notified of a potential air quality issue, prompting immediate precautionary safety measures and evaluation. Subsequent testing confirmed no hazard exists, and normal operations have resumed," chief spokesperson Sean Parnell said in a Thursday statement.
"We express our sincere appreciation to the first responders for their swift actions to ensure the safety of all personnel," he said.
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A hazardous materials team scrubbed several locations in the Pentagon's A ring, the center-most location in the building, according to a Pentagon official.
Approximately 23,000 to 27,000 people work in the Pentagon on any given day.
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Secretary Pete Hegeth's office and chairman of the joint chiefs Gen. Dan Caine's office are not located in the corridors placed under lockdown.
Systems detected a problem with the air quality in part of the building and a device picked up a biohazard scent, the Pentagon source told Fox News.
The Arlington, Virginia, fire department confirmed on X it sent its Hazardous Materials team to support the Pentagon Force Protection Agency’s Hazmat team with the incident.
The last notable Pentagon lockdown was in August 2021, when a Pentagon police officer was killed during a violent incident at the Pentagon Transit Center.
The Pentagon has spent years developing systems designed to detect and contain airborne threats inside the building.
Following the Sept. 11 attacks, officials launched the Pentagon Shield program, which uses sensors, computer modeling and building ventilation controls to help identify chemical, biological and radiological hazards and limit their spread through the Pentagon's five-ring structure.
Building systems can adjust airflow and isolate affected areas while emergency responders assess a potential threat.
Fox News' Liz Friden contributed to this report.