Russian air defence troops downed a Ukrainian drone as it approached an air base in southern Russia and three people died after being struck by debris, Russian news agencies said Monday.
It was the second attack on the Engels base this month. Engels, in the southern Saratov region, lies more than 600 kilometres (370 miles) from Ukraine.
"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 defence 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 defence 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.
He warned locals against spreading "fake information", citing Russia's strict laws adopted in the wake of its Ukraine offensive at the end of February.
"All stories about the evacuation from the city are blatant lies, created far from the borders of our country," he said.
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.
Russian President Vladimir Putin has used the concept of "historical Russia" to argue that Ukrainians and Russians are one people -- undermining Kyiv's sovereignty and justifying his 10-month offensive in Ukraine.
He said Russia's "geopolitical opponents (were) aiming to tear apart Russia, the historical Russia".
