  We present our observations of electromagnetic transients associated with
GW170817/GRB 170817A using optical telescopes of Chilescope observatory and Big
Scanning Antenna (BSA) of Pushchino Radio Astronomy Observatory at 110MHz. The
Chilescope observatory detected an optical transient of $\sim19^m$ on the third
day in the outskirts of the galaxy NGC 4993; we continued observations
following its rapid decrease. We put an upper limit of $1.5\times10^{4}$ Jy on
any radio source with a duration of 10-60 s which may be associated with
GW170817/GRB 170817A. The prompt gamma-ray emission consists of two distinctive
components - a hard short pulse delayed by $\sim2$ seconds with respect to the
LIGO signal and softer thermal pulse with $T\sim 10 $ keV lasting for another
$\sim2$ seconds. The appearance of a thermal component at the end of the burst
is unusual for short GRBs. Both the hard and the soft components do not satisfy
the Amati relation, making GRB 170817A distinctively different from other short
GRBs. Based on gamma-ray and optical observations, we develop a model for the
prompt high-energy emission associated with GRB 170817A. The merger of two
neutron stars creates an accretion torus of $\sim10^{-2} M_\odot$, which
supplies the black hole with magnetic flux and confines the
Blandford-Znajek-powered jet. We associate the hard prompt spike with the
quasispherical breakout of the jet from the disk wind. As the jet plows through
the wind with subrelativistic velocity, it creates a radiation-dominated shock
that heats the wind material to tens of kiloelectron volts, producing the soft
thermal component.
