Crews arrived to find massive flames bursting through the roof of the WWII-era north hangar. The wooden structure had been there for decades.
The fire was eventually knocked down as the smoke could be seen for miles during the firefight.
"Due to the dynamic nature of the fire, and the imminent danger of collapse, we have determined the most operationally sound method is to allow the structure to collapse, at which point ground crews can move in closer, and aggressively work to extinguish the fire," the OCFA said in a statement around daybreak.
"It’s so sad. I’ve been in Irvine/Tustin my whole life," University of California, Irvine student Connor Ruffalo said. "This is such a spectacle. I have no idea when I’ll see something like this again."
The hangars stand 17 stories high, and are over 1,000 feet long and 300 feet wide. They were, and still are two of the largest wooden structures ever built, according to the Tustin Hangars website.
The hanger once housed blimps used in WWII and have been featured in films and TV shows including "JAG," "The X Files," and "Pearl Harbor."
Arson investigators were called to the scene and the public was advised to avoid the area.
Smoke is currently impacting only the immediate area, according to South Coast Air Quality Management District. But officials did warn that strong Santa Ana winds are expected Wednesday morning, which could potentially push remaining smoke toward the southwest.
For those living in an area impacted by windblown dust or ash, officials said to limit outdoor exposure or vigorous physical activity, and to run air conditioning or air purifier units if possible. Officials urge those in the area to avoid burning wood in fireplaces or fire pits.
City News Service contributed to this report.