  Recent discovery of the X-ray neutral iron line (Fe I K\alpha at 6.40 keV)
around several supernova remnants (SNRs) show that MeV cosmic-ray (CR) protons
are distributed around the SNRs and are interacting with neutral gas there. We
propose that these MeV CRs are the ones that have been accelerated at the SNRs
together with GeV-TeV CRs. In our analytical model, the MeV CRs are still
confined in the SNR when the SNR collides with molecular clouds. After the
collision, the MeV CRs leak into the clouds and produce the neutral iron line
emissions. On the other hand, GeV-TeV CRs had already escaped from the SNRs and
emit gamma-rays through interaction with molecular clouds surrounding the SNRs.
We apply this model to the SNRs W28 and W44 and show that it can reproduce the
observations of the iron line intensities and the gamma-ray spectra. This can
be another support of a hadronic scenario for the gamma-ray emissions from
these SNRs.
