  In the cosmological blast-wave model for gamma ray bursts (GRBs), high energy
(> 10 GeV) gamma-rays are produced either through Compton scattering of soft
photons by ultrarelativistic electrons, or as a consequence of the acceleration
of protons to ultrahigh energies. We describe the spectral and temporal
characteristics of high energy gamma-rays produced by both mechanisms, and
discuss how these processes can be distinguished through observations with
low-threshold Cherenkov telescopes or GLAST. We propose that Compton scattering
of starlight photons by blast wave electrons can produce delayed flares of GeV
-- TeV radiation.
