  We present a spectral analysis of 35 GRBs detected with the HETE-2 gamma-ray
detectors (the FREGATE instrument) in the energy range 7-400 keV. The GRB
sample analyzed is made of GRBs localized with the Wide Field X-ray Monitor
onboard HETE-2 or with the GRB Interplanetary Network. We derive the spectral
parameters of the time-integrated spectra, and present the distribution of the
low-energy photon index, alpha, and of the peak energy, e_peak . We then
discuss the existence and nature of the recently discovered X-Ray Flashes and
their relationship with classical GRBs.
