Steve,
We are located in Florida and have over 4,000 lakes under contract for lake management. I can tell you that yours is not the only pond that had the unfortunate fish kill.
As the earlier post indicated, it is most likely related to a turnover of the lake that brought the anoxic water to the surface.
The combination of the wind and cold rains, (It felt cold when I stepped outside during the storms) allowed the lake to for lack of better terms, filp flop.
We have systems and services available that can eliminate this from happening again. I would look forward to speaking with you regarding this.