As you have 5 cats, you have probably experienced this.

Cats can be so stealthy, sneaking up on one another, or a toy, then POUNCE. BUT . . . they can also, each one individually, sound like a herd of elephants!

About once a week, 3 or 4 of mine will all come charging up from the cellar together. (I keep their litter boxes down there.) Never fails to give me pause and wonder, "What the heck???"