It is by now recognized that GRBs can accelerate protons to relativistic en
ergies and that high density media may be present nearby the source. We com
pute the high-energy gamma -ray and neutrino fluxes from the decay of pions
produced through the interaction of accelerated protons with nucleons in t
he surrounding medium. Then, we estimate the Aux of high-energy muons induc
ed on a detector by upward-going neutrinos interacting: through charge curr
ent processes with the surrounding matter.