A file image of a Russian Air Force Mil Mi-8 attack helicopter, the type of which was reportedly shot down.
CNN  — 

Russia’s air force may have just suffered one of its worst days since the Ukraine war began. Unconfirmed reports say that four of its aircraft were shot down within Russian territory, in what would mark a significant coup for Ukraine.

There are conflicting accounts about how many planes and helicopters may have been brought down inside the Russian region of Bryansk, but one Russian media outlet says that at least two combat aircraft – an Su-34 and an Su-35 – and two Mi-8 helicopters crashed.

Ukraine has not confirmed its air defenses were involved in the reported downing of the Russian aircraft on Saturday, but says the aircraft “ran into some trouble.”

Bryansk is on the border with Ukraine and has seen previous attacks blamed on Kyiv.

Multiple crashes within Russian territory at the same time would be unprecedented. Some analysts believe Ukrainian air defenses may have been pushed forward as the Russian air force uses more “glide munitions” that can fire at targets from distance.

The Ukrainian air force spokesman, Yuriy Ihnat, said Sunday that a Russian “strike air group attacked Ukraine from the north, from Bryansk Oblast. They do this almost every day. They carry out strikes with guided bombs.”