Several floors of the Pentagon building in the United States were placed under lockdown after an “air quality issue” was detected, prompting a hazardous materials (hazmat) response and emergency protocols.

According to a statement from Pentagon spokesperson Sean Parnell, the building’s internal systems identified an “air quality issue necessitating precautionary measures until we determine its significance.”

“The Department is executing standard protection protocols, including a shelter-in-place order for the affected area,” Parnell said.

Following the alert, Arlington Fire & Emergency Medical Services (EMS) responded to the scene and confirmed on social media that they were dealing with a hazardous materials incident.

Reports from US media indicated that police officers inside the building were seen wearing gas masks and full chemical protective gear as a precautionary measure.

The Pentagon, which serves as the headquarters of the US Department of Defense, hosts more than 20,000 government employees working across its vast facility.

Authorities have not yet released further details regarding the cause of the air quality alert, and investigations are ongoing. (ILKHA)