From your given extensions, I am sure that it was Jigsaw Ransomware affecting your computers.
For a complete removal guide, you can visit this link:
Recovering files renamed to .fun, .kkk, .btc, .gws extensions can also be done using the tools provided on the same page.
Keep in mind that you must make a backup copy of the compromised files before running any decryptor program. If in case anything goes wrong with the files, at least you still have the original copy.