Wow, I was surprised to find .jpg files in the zip and it's a shame that the border can't be removed, but this is an impressive icon collection nonetheless. I saw that the 'fire' icon was a little weird and found it via google search instantly, but since it was from a US-Government website, it can be used under public domain terms :)

If you have a layered file with these icons, please, please upload it. they would be much more useful without the gradient borders!

So can all this images be safely used as cc0?

Great asset. Created a game using this
https://fancyhat.itch.io/m3-defence

this is great, thank you