Russia has seen the biggest drone assault on its territory since it launched its war on Ukraine while Moscow killed two men in a near-simultaneous bombardment on Kyiv, as the aerial intensity of the conflict ratcheted up.

Six Russian regions including Moscow came under attack early Wednesday, while in the city of Pskov, near the Estonian border, several transport planes were reportedly damaged when drones targeted an airport.

Russian officials haven't reported any casualties, and claimed to have thwarted almost all of the strikes.

Kyiv officials meanwhile said Russia hit the Ukrainian capital with a "massive" bombardment overnight. "Kyiv has not experienced such a powerful attack since spring," Serhii Popko, the head of the city's Military Administration, said on Telegram.

Popko said several groups of drones were traveling towards Kyiv "from different directions" and later missiles were launched towards the capital. More than 20 "enemy targets" were destroyed by air defense forces, he added.

Two people were killed -- men aged 26 and 36 years old -- and three people sustained injuries of varying severity from falling debris, according to the Kyiv City Military Administration.

Across the country, Ukraine downed 28 cruise missiles and destroyed 15 out of 16 drones launched overnight, the Commander in Chief of Ukraine's Armed Forces, Valerii Zaluzhnyi, said Wednesday.

"The trees were on fire. There was lot of smoke ... shrapnel went through the thick cabinet on my balcony," Yelena Yemelyanova, 69, told CNN on Wednesday in Kyiv.

"The wave of the blast swung me to the corridor wall. Everything fell from the kitchen cabinets," she said. "The front door of the apartment was blown out."

Another resident in the proximity of one of the blasts, Victor Savchuk, told CNN that his 15-year-old grandson was left soaked in blood after debris fell on him. "The sirens go off every day one, two three times a day. We don't know what to expect," Savchuk said.

Flights shut down in Moscow

Ukraine has increasingly been emboldened to hit strategic targets inside Russia through the air in recent weeks, even as it suffers assaults on its own cities, setting up a new phase of the conflict defined by Kyiv's apparent efforts to wear down domestic Russian support for the war.

Following the raids all four Moscow airports temporarily suspended flight operations. At least 11 passenger flights were redirected to alternate airports, causing disruption, state news agency TASS reported citing the Federal Air Transport Agency. Later updates indicated that the airports resumed normal operations.

The governor of Bryansk, which borders Ukraine, said air defenses thwarted a Ukrainian drone attack on a television tower early on Wednesday. Aleksandr Bogomaz said a fire had been extinguished and emergency services were working at the site of the alleged attack.

The wave of strikes came hours after the governor of Russia's southwestern Bryansk region said that the Ukrainian military had fired at the village of Klimovo with multiple launch rocket systems, and claimed an unspecified number of deaths.

An airport in Russia's western city of Pskov, used for both civilian and military aircraft, also came under drone attacks late on Tuesday, according to the region's governor.

Mikhail Vedernikov posted a video showing what appears to be a large plume of smoke coming from behind buildings in what looks like a residential area. Russian state news agency TASS reported that "as a result of drone attacks four Il-76 aircraft were damaged," in Pskov. A fire broke out and two aircraft were engulfed in flames, TASS said, citing emergency services.

Flights over Pskov and the region were restricted, TASS added.

Fierce fighting and sluggish movement is meanwhile continuing in the ground war. Ukraine stepped up its evacuations of children from the frontline town of Kupiansk on Tuesday, as Russian forces continued to bear down on the battered city.

Kupiansk lies in northeastern Ukraine, more then 200 miles from the southern front, where Ukrainian troops are making slow progress in their counter-offensive. The dueling theaters of fighting may indicate an attempt by each side to draw opposition troops away from their primary targets.

The Ukrainian military says that its forces have made further progress in a part of the southern front, towards the villages of Novodanylivka and Verbove. If successful in the Verbove area, the Ukrainians would widen a wedge of territory they have taken as they push south towards the strategic hub of Tokmak, which is occupied by the Russians.