Pentagon floors on lockdown after 'hazardous materials' incident

Several floors in the Pentagon building have been placed on lockdown following the detection of an "air quality issue", prompting hazardous material (hazmat) response teams to the scene.

The building's systems detected an "air quality issue necessitating precautionary measures until we determine its significance," said Pentagon spokesperson Sean Parnell in a statement.

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

The Pentagon is being assisted by Arlington Fire & EMS, who posted on social media that they are responding to a hazardous materials incident.

Police in the building are wearing gas masks and full chemical protective gear, US media reported.

The Pentagon serves as the US Defence Department's headquarters, with more than 20,000 government employees working in the building.