Impact and Movement:
* Thump, thump, thump: Heavy, solid footsteps.
* Clack, clack, clack: Lighter, faster steps, perhaps on wooden stairs.
* Bang, bang, bang: Hard, forceful steps, maybe someone is rushing in a panic.
* Swoosh, swoosh, swoosh: The sound of fabric moving as someone runs down the stairs.
* Screech, screech, screech: The sound of someone sliding down the stairs, perhaps losing control.
Other Sounds:
* Rumble: The sound of the stairs themselves vibrating as someone runs down.
* Echo: The sound of the footsteps echoing in a stairwell.
* Whizz: The sound of someone going down the stairs very quickly.
* Crash: The sound of someone falling down the stairs.
Descriptive Phrases:
* A rush of footsteps...
* A pounding on the stairs...
* A frantic scramble...
* A clatter of descending feet...
The specific words you choose will depend on the scene you're trying to create and the mood you want to evoke.