  The energy source has remained to be the great mystery in understanding of
the gamma-ray bursts (GRBs) if the events are placed at cosmological distances
as indicated by a number of recent observations. The currently popular models
include (1)the merger of two neutron stars or a neutron star and a black hole
binary and (2)the hypernova scenario of the collapse of a massive member in a
close binary. Since a neutron star will inevitably collapse into a black hole
if its mass exceeds the limit $M_{max}\approx3M_{\odot}$, releasing a total
binding gravitational energy of $\sim10^{54}$ erg, we explore semi-empirically
the possibility of attributing the energy source of GRB to the accretion-
induced collapse of a neutron star (AICNS) in a massive X-ray binary system
consisting of a neutron star and a type O/B companion. This happens because a
significant mass flow of $\sim10^{-3}$--$10^{-4}M_{\odot}$ yr$^{-1}$ may be
transferred onto the neutron star through the Roche-lobe overflow and primarily
during the spiral-in phase when it plunges into the envelope of the companion,
which may eventually lead to the AICNS before the neutron star merges with the
core of the companion. In this scenario, a ``dirty'' fireball with a moderate
amount of beaming is naturally expected because of the nonuniformity of the
stellar matter surrounding the explosion inside the companion, and a small
fraction ($\sim0.1%$) of the energy is sufficient to create the observed GRBs.
In addition, the bulk of the ejecting matter of the companion star with a
relatively slow expansion rate may act as the afterglow. Assuming a
non-evolutionary model for galaxies, we estimate that the birthrate of the
AICNS events is about 2 per day within a volume to redshift $z=1$ for an
$\Omega_0=1$ universe, consistent with the reported GRB rate.
