A malfunctioning biosensor triggered one of the most intense security responses at the world's largest low-rise office building on Thursday, 11 June 2026, after Pentagon air-quality systems detected a possible anthrax presence, sending hazmat crews in full chemical gear rushing through its corridors and forcing roughly 2,500 personnel to shelter in place.
The incident began around 09:00 ET, when first-responder radio traffic registered what sources described as 'a positive anthrax system alert', accompanied by reports of a suspicious odour and at least one person experiencing chest pain in the building's inner courtyard. Within hours, corridors that usually bustle with the country's most senior military and civilian defence staff had been sealed off, and the building's own police force was patrolling in gas masks.
