The Pentagon was partially locked down and partially evacuated on Thursday after building monitoring systems detected an air-quality issue. A Pentagon sensor system detected the possible presence of anthrax, but the sensor system was malfunctioning, causing a false alarm. A full emergency response was triggered, including gas masks and hazmat teams. The Pentagon went into a shelter-in-place and some floors were evacuated. The Pentagon resumed normal operations after the lockdown. No one in the public found out about the lockdown until one hour later because the Pentagon had press locked out.