Multiple floors and corridors inside the Pentagon have been locked down and others are being evacuated due to a “hazardous materials incident,” three sources familiar and the local fire department said.

Pentagon spokesman Sean Parnell confirmed Thursday that systems within the Pentagon “have detected 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. “Response teams are in place and ready to support building occupants.”