Russia said that it shot down a Ukrainian drone near Engels airbase in Russia's Saratov region.
Falling debris from the downed drone killed three Russian military personnel, authorities said.
The drone, which was shot down near the Engels military airbase in Russia's Saratov region, hit and fatally wounded the staff members, a statement from the Defence Ministry, published by Russian news agencies, said.
Although Ukraine has not claimed responsibility for the drone, Ukrainian Air Force spokesperson Yurii Ihnat told national television Monday that incidents like this are the "consequences of Russian aggression," ABC News reported.
Ukraine has also not taken responsibility for other recent drone attacks on Russian airbases.