The Pentagon briefly went into lockdown on Thursday due to a “Hazmat incident” caused by a false alarm inside the building.

Arlington Fire and EMS initally reported on social media, “ACFD units, including our Hazardous Materials Team, are currently operating at the Pentagon in support of PFPA’s Hazmat Team during a hazardous materials incident.”

CNN’s Haley Britzky, inside the building, added minutes later, “Multiple floors and corridors inside the Pentagon have been locked down and others are being evacuated, three sources familiar with the situation told CNN. 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.”

Britzky reported an hour or so later, “Sources telling me + @PamelaBrownCNN that the lockdown was due to a false alarm.”

The incident came amid ongoing hostilities between the U.S. and Iran.

CNN covered the incident live as news broke, with anchor Wolf Blitzer noting, “The Pentagon, yes, the Pentagon, is on lockdown. I want to go straight to CNN’s Brian Todd for us. Update our viewers, Brian, what’s going on?”

“Right, Wolf. This is reporting from our colleague Haley Britsky that multiple floors and corridors inside the Pentagon have been locked down and others are being evacuated. That’s according to three sources familiar with the situation. Pentagon spokesman Sean Parnell confirms that systems within the Pentagon quote, ‘have detected an air quality issue, necessitating precautionary measures until we determine its significance,’ end quote,” Todd reported, adding:

So this is an air quality issue that is affecting the Pentagon, and according to our sources, multiple floors and corridors have been locked down and others are being evacuated. I have a little bit more detail here. According to the Pentagon Force Protection Agency, the Hazardous Materials Response Team is now responding to this incident at the Pentagon, with the assistance of the Arlington County, Virginia Fire Department.

That is according to a Pentagon spokesperson, or the Fire Department spokesperson, Captain Jamie Jill. A post on social media from the Arlington Fire and EMS said that the Arlington County Fire Department hazardous materials team is operating at the Pentagon, quote, “during a hazardous materials incident.” So there is something apparently affecting the air quality of the Pentagon. A little bit more detail here, according to our sources: floors 2 through 5 in corridors 4 through 7 of the Pentagon complex have been locked down. That’s according to two sources.

A third source told CNN that police in the building are wearing gas masks and full chemical protective gear. So this does appear to be an air quality hazmat situation that is again causing multiple floors and corridors inside the Pentagon to be locked down and other floors and corridors to be evacuated. We’re getting more detail as we can here, guys, but that is what we can tell you right at this moment. Multiple floors evacuated, multiple floors locked down at the Pentagon. According to Pentagon spokesman Sean Parnell, they have detected an air quality issue necessitating precautionary measures until they determine the significance of this event.

This is a developing story and has been updated.

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