The Pentagon experienced a hazardous materials incident that prompted a large response from Hazmat crews and law enforcement, leading to a partial lockdown and shelter-in-place order due to air quality concerns. Although some floors were evacuated, sources later indicated that the situation was the result of a false alarm. Emergency response teams were deployed to address potential air hazards, and multiple floors remained under lockdown while teams conducted searches. The situation unfolded just hours before a significant public event, heightening the urgency of the response.