By using a particle code including atomic and relaxation processes, we investigated the ionization dynamics of a carbon film irradiated by an intense laser pulse. We found two types of ionization dynamics, namely, a fast time scale convective propagation of the ionization front with C4+ triggered by induced plasma waves, and a slow front with C5+ and C6+ triggered by heated electrons due to non-local thermal conduction. Thus, ionization dynamics in solids are found to evolve through multiple stages.