documentclass[14pt,twoside]{extreport}
usepackage{type1ec}
usepackage[T2A]{fontenc}
usepackage[utf8]{inputenc}
usepackage[english]{babel}
usepackage{multirow}
usepackage{array}
usepackage{longtable}
usepackage{tabu}
usepackage[unicode=true]{hyperref}


begin{document}

begin{longtabu} to linewidth {|*4{X[25,C]|}}
 caption{Table caption%
 label{tab:first}}\hline
 Column A   & Column B  & Column C  & Column D\hline
 endhead
 Cell A & Cell B    & Cell C    & Cell D\hline
 multicolumn{4}{|c|}{parbox{0.95linewidth}{vspace{10pt}%
  begin{enumerate}%
   item First item;%
   item Second item;%
   item Third item;%
   item Fourth item.%
  end{enumerate}%
  vspace{10pt}}}\hline
end{longtabu}

Test link to table~ref{tab:first}.

end{document}