This was very unexpected. I had parked my car on the street less than a block away from the fire station while I was in Harpers Ferry (my university is only a 15 minute drive away) and as I was about to get into my car and go, the siren went off. I quickly noticed that it was blowing very short cycles, it barely wound up all the way. It cycled about 6 or 8 times, and each one sounded just like the one in the video. My guess is that it's to reduce disturbance to the historic downtown and park. Unfortunately I only managed to catch the last windup on film. Also, the lower horn that would be facing the camera is missing.
https://www.youtube.com/watch?v=S3p2IPsE1E4