Investigators are trying to determine what caused an explosion that sent a plume of potentially dangerous smoke into the air at a Florida Air Force Base.

No injuries were reported after the explosion Wednesday morning at the McKinley Climatic Lab, but several firefighters were treated for dehydration after putting out the fire.

Base spokeswoman Jasmin Porterfield tells the Pensacola News Journal the smoke, identified at methyl chloride, didn’t pose a health hazard to the public, but an area was evacuated as a precaution.

The lab can simulate temperatures ranging from minus 60 to 160 degrees Fahrenheit and test engineers test everything from the survival skills of troops to heat and cold tolerances of fighter jets.

Porterfield says 27 military contractors and six Department of Defense employees work in the building.

(AP)