  We propose a new mechanism for high energy gamma ray burst in Supernova type
I (SNI) explosion. Presupernova is assumed to be a binary system comprised of a
red giant and a white dwarf with a wind accretion. The accretion flow
terminates by the accretion shock in the vicinity of the white dwarf at the
distance of the order of the accretion radius. The gas inside the accretion
radius constitutes the main body of a target for gamma ray production by $pp$
collisions.\par The supernova explosion and the shock propagation in the white
dwarf result in the hydrodynamical acceleration of the outer layers of the
star. The spectrum of accelerated particles is steep and the maximum energy
does not exceed $1000$ $GeV$.\par The gamma ray burst is produced due to
interaction of the accelerated particles with the gas in the binary system.
Most of the photons have energies about $100$ $MeV$, the total number of the
emitted photons is between $10^{46}$ and $10^{47}$. The gamma ray burst might
have one or two precursors. The first one is produced during the shock breakout
when the shock approaches the star surface and crosses it.\par The calculations
are valid in the case of a weak magnetic field. The case of strong magnetic
field will be considered in part II (in preparation).
