Officials at Eglin Air Force Base, Florida, are warning personnel to avoid a perimeter around McKinley Climatic Lab after an unexplained explosion occurred at the on-base facility Wednesday.
"A little before 10 a.m., an explosion occurred at McKinley Climatic Lab," Eglin officials said in a Facebook post.
No injuries have been reported.
First responders established a 1,000-ft perimeter, and surrounding areas were evacuated, the post said. Officials said to avoid contact with smoke from the blast, even as it continues to dissipate.
Officials first warned the smoke may have contained methyl chloride, but later said, "It has not been determined that the smoke contained methyl chloride. However the incident occurred in an area within close proximity of said chemical."
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Methyl chloride can be used as a cooling mechanism; its use has been curtailed, however, because of toxic effects and flammability.
Officials ordered a temporarily shelter in place for offices stationed between Eglin Boulevard and Van Matre Avenue -- roughly a three mile stretch -- and asked personnel to turn off their heating, ventilation and air conditioning systems to avoid circulating smoke in facilities.
Eglin spokeswoman Ilka Cole told Military.com there is no explanation for what caused the explosion at this time. She could not say whether anyone was in the building at the time of the explosion, but said "people normally work in that building."
"We will provide updates as we receive them. The cause is currently under investigation," Cole said.
The McKinley Lab is responsible for high-range weather testing of military and commercial aircraft, munitions and weapons.
Cole could not say how much damage the explosion has caused, or if the blast aftermath will shut down the facility until the investigation is complete.