Flames engulfed a historic World War II-era blimp hangar at the former Tustin Air Base today, with the intensity of the massive fire forcing crews to pull back and wait for the local landmark to collapse before moving in to extinguish the blaze.

“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 Orange County Fire Authority said in a statement around daybreak.

A photo of the scene the Orange County Fire Authority posted on X, formerly Twitter, at 6:25 a.m. on Tuesday, Nov. 7, 2023.

The blaze — its cause not immediately known — ignited early Tuesday morning at one of the two giant hangars that were built in 1942 and once housed blimps used in World War II.

Listed on the National Register of Historic Places, they stand 17 stories high, are over 1,000 feet long and 300 feet wide — and are two of the largest wooden structures ever built, according to the website Tustin Hangars.

Crews responded after 1:30 a.m. to Valencia Avenue and Armstrong Road, where they found massive flames bursting through the roof, according to the OCFA.

Pieces of the roof were seen slowly falling to the ground as the fire continued to burn. At one point overnight, the fire authority called in a helicopter to help put out the blaze. Motorists were asked to avoid the area.

Arson investigators were sent to the scene to determine the cause of the fire.

Police will remain at the scene around the clock for security and to help monitor for embers, Tustin police Lt. Ryan Coe said.

The historic hangars have been featured in television and films, including  “JAG, ” “The X Files,” “Austin Powers,”  “Pearl Harbor” and “Star Trek.”

Anyone with information that might be helpful to investigators was asked to call 714-573-3225. Orange County Crime Stoppers will accept anonymous tips at (855) TIP-OCCS.