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We present our observations of electromagnetic transients associated withGW170817/GRB 170817A using optical telescopes of Chilescope observatory and BigScanning Antenna (BSA) of Pushchino Radio Astronomy Observatory at 110MHz. TheChilescope observatory detected an optical transient of $\sim19^m$ on the thirdday in the outskirts of the galaxy NGC 4993; we continued observationsfollowing its rapid decrease. We put an upper limit of $1.5\times10^{4}$ Jy onany radio source with a duration of 10-60 s which may be associated withGW170817/GRB 170817A. The prompt gamma-ray emission consists of two distinctivecomponents - a hard short pulse delayed by $\sim2$ seconds with respect to theLIGO 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 burstis unusual for short GRBs. Both the hard and the soft components do not satisfythe Amati relation, making GRB 170817A distinctively different from other shortGRBs. Based on gamma-ray and optical observations, we develop a model for theprompt high-energy emission associated with GRB 170817A. The merger of twoneutron stars creates an accretion torus of $\sim10^{-2} M_\odot$, whichsupplies the black hole with magnetic flux and confines theBlandford-Znajek-powered jet. We associate the hard prompt spike with thequasispherical breakout of the jet from the disk wind. As the jet plows throughthe wind with subrelativistic velocity, it creates a radiation-dominated shockthat heats the wind material to tens of kiloelectron volts, producing the softthermal component.

GRB170817A associated with GW170817: multifrequency observations and modeling of prompt gamma-ray emission