The time dependence of extreme ultraviolet (EUV) fluorescence following an ionizing radiation event in liquid helium is observed and studied in the temperature range from 250 mK to 1.8 K. The fluorescence exhibits significant structure including a short $(\ensuremath{\sim}10\mathrm{ns})$ strong initial pulse followed by single photons whose emission rate decays exponentially with a $1.6\ensuremath{-}\ensuremath{\mu}\mathrm{s}$ time constant. At an even longer time scale, the emission rate varies as ``1/time'' (inversely proportional to the time after the initial pulse). The intensity of the ``1/time'' component from $\ensuremath{\beta}$ particles is significantly weaker than those from $\ensuremath{\alpha}$ particles or neutron capture on ${}^{3}\mathrm{He}.$ It is also found that for $\ensuremath{\alpha}$ particles, the intensity of this component depends on the temperature of the superfluid helium. Proposed models describing the observed fluorescence are discussed.