Hazmat units respond to Pentagon 'hazardous materials' incident

Specialized hazardous materials teams from the Arlington County Fire Department (ACFD) joined Pentagon security forces Thursday to address a "hazardous materials incident" at the US military headquarters.

The Pentagon's "sophisticated systems" detected an "air quality issue necessitating precautionary measures until we determine its significance," the agency said in a statement.

The department is executing a shelter-in-place order for the affected area as “standard protection protocols.”

"Response teams are in place and ready to support building occupants," it said.

The local fire department, meanwhile, said its units "are currently operating at the Pentagon in support of PFPA’s (Pentagon Force Protection Agency) Hazmat Team.

While multiple floors faced lockdowns and police donned chemical protective gear, sources familiar with the situation told CNN that the alert was a false alarm. The Pentagon did not immediately confirm or deny this report.