  The existence of high-energy astrophysical neutrinos has been unambiguously
demonstrated, but their sources remain elusive. IceCube reported an association
of a 290-TeV neutrino with a gamma-ray flare of TXS 0506+056, an active
galactic nucleus with a compact radio jet pointing to us. Later, radio-bright
blazars were shown to be associated with IceCube neutrino events with high
statistical significance. These associations remained unconfirmed with the data
of independent experiments. Here we report on the detection of a rare neutrino
event with the estimated energy of 224+-75 TeV from the direction of TXS
0506+056 by the new Baikal Gigaton Volume Detector (Baikal-GVD) in April 2021.
This event is the highest-energy cascade detected so far by the Baikal-GVD
neutrino telescope from a direction below horizon. The result supports previous
suggestions that radio blazars in general, and TXS 0506+056 in particular, are
the sources of high-energy neutrinos, and opens up the cascade channel for the
neutrino astronomy.
