http://www.youtube.com/watch?v=d_wEKM-f8dY - (EXPLICIT LANGUAGE; bad quality) SpectrAlert classic horn/strobes in code-3 (unsynced horn) along w/ smoke detectors.
http://www.youtube.com/watch?v=aLCHGtQ1zeg - See video description.
http://www.youtube.com/watch?v=EuL9EfUHtOE - Fire alarm electronic chime in slow march time.
http://www.youtube.com/watch?v=ZtJHUtW5zXA - (skip to :02) 8" bell in slow march time.
http://www.youtube.com/watch?v=eq-2xwdxURA - (bad quality) You can faintly hear NS alarms in code-3.