“On December 26, at around 01:35 Moscow time (2235 GMT), a Ukrainian unmanned aerial vehicle was shot down at low altitude while approaching the Engels military airfield in the Saratov region,” the TASS news agency reported, quoting the defense ministry.

“As a result of the fall of the wreckage of the drone, three Russian technical servicemen who were at the airfield were fatally injured.”

The defense ministry said no planes were damaged.

Saratov governor Roman Busargin said there was “absolutely no threat” to local residents, adding that no civilian infrastructure had been damaged.

On December 5, Moscow said Ukrainian drones had caused explosions at the Engels airfield and another base in the Ryazan region.

Kyiv had not yet commented on the incident.

Russia has blamed Ukraine for drone attacks on its territory and on Moscow-annexed Crimea before.

In late October, Russia blamed Ukraine for a “massive” drone attack on its Black Sea Fleet in the Crimean port city of Sevastopol.

But the Engels attack was the deepest reported strike into Russian territory since fighting began.