Apply a figure caption inside of a longtable

I'm using the 'longtable' environment to display a number of figures. I'd like to include a caption at the bottom of the first page as a Figure caption, not as a table (so that it also shows up in the list of figures, not list of tables). I found in another post how to define a new 'figcaption', but I'm getting a 'you can't use \hrule here' error when I compile the following code.

It works when I use 'figcaption' outside of the longtable environment, but I need it to be at the bottom of the first page.

Can someone please point me in the right direction?

    \documentclass{article}
    \usepackage{array}
    \usepackage{caption}
    \usepackage{longtable}


    \makeatletter
    \def\figcaption{%
        \refstepcounter{figure}%
        \@dblarg{\@caption{figure}}}
    \makeatother

    \begin{document}
    \listoftables
    \listoffigures

    \begin{longtable}[h]{cc}

    \endfirsthead
    \endhead
    \figcaption{This should be a figure caption}\label{fig:MyFigRef}
    \endfoot
    \endlastfoot

     \rule{5cm}{5cm} & \rule{5cm}{5cm} \\
     \rule{5cm}{5cm} & \rule{5cm}{5cm} \\
     \rule{5cm}{5cm} & \rule{5cm}{5cm} \\
     \rule{5cm}{5cm} & \rule{5cm}{5cm} \\
     \rule{5cm}{5cm} & \rule{5cm}{5cm} \\
     \rule{5cm}{5cm} & \rule{5cm}{5cm} \\

    \end{longtable}

    \end{document}