  Observations of the gravitational-wave (GW) event S190425z registered by the
LIGO/Virgo detectors with the Anti-Coincidence Shield (ACS) of the gamma-ray
spectrometer SPI aboard the INTEGRAL observatory are presented. With a high
probability (>99%) it was associated with a neutron star (NS) merger in a close
binary system. This is only the second event of such type in the history of GW
observations (after GW170817). A weak gamma-ray burst, GRB190425, consisting of
two pulses in ~0.5 and ~5.9 s after the NS merging in S190425z was detected by
SPI-ACS. The pulses had a priori reliability of 3.5 and 4.4 sigma as single
events and 5.5 sigma as a combined event. Analysis of the SPI-ACS count rate
history recorded these days (~125 ks in total) has shown that the rate of
appearance of two close pulses with characteristics of GRB190425 by chance does
not exceed 6.4 x 10^{-5} s^{-1}. We note that the time profile of GRB190425 has
a lot in common with the profile of the GRB170817A burst accompanying the
GW170817 event; that both the NS mergers were the closest (<150 Mpc) of all the
events registered by the LIGO/Virgo detectors; and that there were no confident
excesses of gamma-ray emission over the background detected in any of >30 black
hole merger events recorded to the moment by these detectors. No hard X-ray
flares were detected in the field of view of the SPI and IBIS-ISGRI gamma-ray
telescopes aboard INTEGRAL. This, as well as the lack of detection of gamma-ray
emission from GRB190425 by the GBM monitor of the Fermi observatory assuming
its occultation by the Earth, can significantly reduce the localization area
for the source of this GW event. The estimates of the parameters E_{iso} and
E_{p} for GRB190425 are obtained and compared with the similar parameters for
GRB170817A.
