  Highly variable gamma-ray pulses and X-ray flares in GRB light curves can
result from external shocks rather than central engine activity under the
assumption that the GRB blast-wave shell does not spread. Acceleration of
cosmic rays to 10^{20} eV energies can take place in the external shocks of
GRBs. Escape of hadronic energy in the form of UHECRs leads to a rapidly
decelerating GRB blast wave, which may account for the rapid X-ray declines
observed in Swift GRBs.
