Hazardous materials incident prompts Pentagon lockdown, officials say

Arlington fire dept said units, including its HazMat team, operated at the Pentagon during a hazardous incident report

A hazardous materials ​incident put the Pentagon on lockdown on ‌Thursday as fire officials investigated the air quality issue, defence and fire officials said.

The Arlington County Fire Department said in a post on X that it had units "including our Hazardous Materials Team" operating at the Pentagon during what it described as a "hazardous materials incident".

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. pic.twitter.com/7qzOzbwh8W

— Arlington Fire & EMS (@ArlingtonVaFD) June 11, 2026

The fire department did not provide further details on the nature of the incident.

"The Pentagon has sophisticated systems to ​ensure the safety of the building and ​its occupants. Those systems have detected an ⁠air quality issue necessitating precautionary measures until we ​determine its significance," Pentagon spokesman Sean Parnell said in ​an email.

STATEMENT:

The Pentagon has sophisticated systems to ensure the safety of the building and its occupants. Those systems have detected an air quality issue necessitating precautionary measures until we determine its significance.

The Department is executing standard protection…

— Sean Parnell (@SeanParnellASW) June 11, 2026

"The department is executing standard protection protocols, including a shelter-in-place order for the affected area. Response teams are ​in place and ready to support building occupants."

The ​building was under lockdown, with people evacuated from several floors, ‌CNN ⁠reported, citing unidentified sources. Floors two through five in corridors four through seven have been locked down, CNN said, citing two sources.

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Another source reported seeing emergency ​responders ​wearing full ⁠gas masks and chemical protection suits, CNN said.

A message sent by the Pentagon’s ​security team said additional testing was ​needed ⁠to determine the source of the problem, according to CNN.

The five-sided Pentagon building, hit during the September ⁠11, ​2001, Al Qaeda attacks, is ​one of the world's largest office buildings.