Back during Firestorm, my crew went into the burned out neighborhoods to restore some of the vital phone lines to satellite towers. A coworker of mine was working next to a burned out lot, where the homeowner was searching for his fire proof safe. He found it, and lamented that if it was destroyed, his life would be in chaos.
The man opened the safe, and the contents inside, which were intact, burst into flame.
The trick to those things is that it doesn’t give the things inside the oxygen they need to burn. Here, the man opened the safe, and the stuff inside was super-heated, and now had the oxygen they needed.. It needed time to cool before the safe should have been opened.

11 August 2017. I stood outside my home and watched it burn. I was about to be displaced for an entire year, as my urban condo was gutted and then reconstructed. The fire wasn’t my fault. I live in an urban condo, and my upstairs neighbor, a high-level hoarder with floor-to-ceiling stacks of books and papers with extension cords beneath them, was responsible.

I didn’t have a fire safe, so I can’t answer your question directly. Here’s what I can say. People often speculate about what they’d take with them while fleeing a burning building; perhaps the photo albums, jewelry, or other valuable or sentimental items. Here’s what they do take: nothing. They run for their lives, and they’re happy to be alive.

The upstairs windows were spewing smoke and flames. I grabbed Sadie (dog) and fled. Thank goodness, Martin (cat) hid beneath our bed, below the melee, and survived.

(Social question. I’m free to meander.)

Wow. Can’t help but react to both answers so far.