I bought my own fire alarm (i am an enthusiast) on ebay. I went into my garage to record it. And it didn't work. I tinkered with it a little and got it to work. And this is what it sounds like. Feel free to use with no credit.
Zoom h1 recording, just did press record. Maybe 20 or 30 or more fire engines recorded at distancevery very long recording, but if you need lots of sirens they are plenty.