“This act of revenge, carried out by representatives of the local resistance movement, took place on the premises of the ‘New Post Office’ seized by the Russians,” the agency said.
Russian forces have established their headquarters in Melitopol, a city in southwestern Ukraine that was captured in the early days of the war.
“As a result of the explosion at least three National Guard officers were killed at the headquarters,” officials said.
It said information of any other Russian losses is being verified. Russia’s defence ministry has not commented on the deaths, the identities of the deceased officers or the attack on its headquarters.
Melitopol is among territories Russia captured in the Zaporizhzhia region along with several settlements in the besieged east and south.
Ukraine has launched several attacks in these areas in efforts to recapture them.
Melitopol had a pre-war population of nearly 150,000, and currently serves as a key location to Moscow’s defence of lands it now controls in Ukraine’s south.