Firefighters were called to a home in the 800 block of Medway Road before 3:00 p.m. Thursday.
When they got inside, they found a large number of cats. Most were alive, but at least two were dead.
Once the fire was under control, animal control officers arrived to capture the surviving cats.
At last count, they had retrieved 21.
The homeowner, whom neighbors describe as a hoarder, was not there at the time.
"I did call L & I several times, and one time they did have somebody come out and they cleaned the house out," neighbor Allison Mort told Action News. "They were wearing hazmat suits and they took a bunch of trash out. But that was two years ago, and then it started to get bad again. You could smell it."
The SPCA took the surviving cats in for care.
No word whether charges will be filed, or what sparked the fire.