Russia said on Wednesday that it has prevented one of the largest Ukrainian drone assaults on western Russia to yet, shooting down unmanned aircraft in at least six districts and destroying a Ukrainian naval attack on the occupied Crimean peninsula.

According to Russian officials, the drone assaults damaged Russian military aircraft and affected civilian aviation in the Pskov, Bryansk, Kaluga, Orlov, Ryazan, and Moscow areas.

The most significant attack appeared to be in Pskov about 660 km (411 miles) north of the Ukrainian frontier, near the borders with Estonia and Latvia, where Russian officials said four Il-76 military transport planes were damaged.

Ukraine, which has yet to achieve a major success in its summer ground counteroffensive, has struck deep into Russia in recent months, including an attack on the Kremlin in May and numerous drone attacks on civilian targets in Moscow.

Ukraine typically does not comment on who is behind attacks on Russian territory, although officials have publicly expressed satisfaction over them.

Footage published by Pskov’s governor on Telegram showed smoke rising from a large fire as the sounds of sirens and an explosion ring out. Other reports on Telegram channels showed anti-aircraft systems in action around the city, which is just 32 km (20 miles) east of the Estonian border.

Tass news agency, quoting emergency services, said four Il-76 transport aircraft, long the workhorse of the Russian military, were damaged at the military airfield. Two of the planes “burst into flames”, it added.

Civilian flights were cancelled at the local airport. The airspace around Moscow’s Vnukovo airport was closed briefly, TASS reported.

Russia said Ukrainian drones tried to attack a TV tower over the Bryansk region. No casualties were reported.

A Russian aircraft also destroyed four Ukrainian fast-attack boats carrying up to 50 paratroopers in an operation on the Black Sea, the military said.

Russia launched air attacks of its own on Wednesday morning, killing at least two people in Kyiv, Mayor Vitali Klitschko wrote on the Telegram messaging app.

Reuters was not able to independently verify the reports and there was no immediate comment from Ukraine.