  We report on the close similarity of coronal mass ejection (CME) properties
in ground level enhancement (GLE) in solar energetic particle (SEP) events and
sustained gamma ray emission (SGRE) from the Sun as indicated by low frequency
type III radio bursts observed in the interplanetary medium. The complex type
III bursts have an average 1 MHz duration of 36 and 34 min in the SGRE and GLE
events, respectively. Similarly, the CMEs underlying SGRE and GLE have average
space speeds of 1866 and 2084 km/s, respectively. These are larger than the
corresponding values (32 min, 1407 km/s) for a control sample of type III
bursts associated with frontside halo CMEs with sky plane speed exceeding 800
km/s. These results are consistent with the idea that energetic CME driven
shocks accelerate particles to very high energies that are responsible for GLE
and SGRE events.
