The Russian Defense Ministry said Ukrainian drone attacks caused explosions at two airfields in the Saratov and Ryazan regions on Monday, leaving three dead.
On Monday morning "the Kyiv regime attempted to strike the Dyagilevo airfield in the Ryazan region, and the Engels airfield in the Saratov region, with Soviet-made drones," the ministry said in a statement, adding that three soldiers had been killed.
The drones aiming to "disrupt Russian long-range aircraft" were intercepted, the ministry said, but debris fell and exploded on the airfields.
Four other soldiers were wounded and taken to medical facilities.
Two planes were slightly damaged, according to the statement.
Russian President Vladimir Putin was briefed about the incidents, Kremlin spokesman Dmitry Peskov said earlier on Monday.
"From all relevant services, the president regularly receives information about everything that happens," Peskov added, declining to provide further details.
In the same statement, the Russian Defense Ministry said it carried out a "massive attack on Ukrainian military command systems and related defense, communications, energy and military facilities" at around 12:00 GMT.
"All 17 targets were hit," the ministry said.