The agency cites one of his relatives. According to him, Kalashnykov has been living in Kyiv over the past time.
The murder took place near his home.
The relative also said that Kalashnykov had been threatened with physical violence for political views recently, in particular for his appeal to widely celebrate the 70th anniversary of "Victory in the Great Patriotic War."
He also received messages with relevant threats.
According to the relative, the murder occurred around 8 p.m. at Vynohradar neighborhood (Podil district of Kyiv) in the house where he lived.
"He got up to the 8th floor and was killed by a gunshot," the interlocutor said.
His wife ran out to the noise and called the police who are currently working at the scene.
Earlier, the SBU was checking Kalashnykov's statements as to the threats to national security.