In a rarity, both Ukrainian and Russian officials confirmed the blasts, which struck deep inside Russian-controlled territory. And both explosions appeared to be the work of what analysts say is a growing partisan resistance movement — one fueled by increasingly brutal Russian repression and worsening humanitarian conditions.

By their very nature, the clandestine activities of any insurgency are murky and often impossible to verify independently. It is as much in the interest of Ukrainians to play up talk of rebellion as it is for Russians to play it down.

But the explosion that injured the Enerhodar mayor, Andrei Shevchik, is one of more than a dozen high-profile attacks in recent weeks that analysts say indicate increased partisan activity aimed at Russian occupation forces in the Kherson and Zaporizka regions of southern Ukraine.