Russia attacked the Ukrainian capital in the early hours of Sunday morning, striking at least two residential buildings, Kyiv Mayor Vitali Klitschko said, as elsewhere Russian troops consolidated their gains in the east.

Associated Press (AP) journalists in Kyiv saw rescue services battling flames and rescuing civilians. Klitschko said four people were hospitalized with injuries and a 7-year-old girl was pulled alive from the rubble.

Ukrainian lawmaker Oleksiy Goncharenko wrote on the Telegram messaging app that "according to prelim data 14 missiles were launched against Kyiv region and Kyiv."

Before Sunday’s early morning attack, Kyiv had not faced any such Russian airstrikes since June 5.

Klitschko told journalists that he believed "it is maybe a symbolic attack" ahead of this week's NATO summit in Madrid.

Two more explosions were later heard in Kyiv, but their cause and possible casualties were not immediately clear.

Meanwhile, Russian forces have been seeking to swallow up the last remaining Ukrainian stronghold in the eastern Luhansk region, pressing their momentum after taking full control Saturday of the charred ruins of Severodonetsk and the chemical plant where hundreds of Ukrainian troops and civilians had been holed up.

Serhiy Haidai, governor of the Luhansk region that includes Severodonetsk, said Sunday that Russia was conducting intense airstrikes on the adjacent city of Lysychansk, destroying its television tower and seriously damaging a road bridge.

"There's very much destruction – Lysychansk is almost unrecognizable," he wrote on Facebook.

Also Sunday, U.S. President Joe Biden said the United States and other G-7 leading economies intend to announce a ban on imports of gold from Russia. They hope that measure will further isolate Russia economically over its invasion of Ukraine.

Senior Biden administration officials said gold is Moscow’s second largest export after energy, and that banning imports would make it more difficult for Russia to participate in global markets.

Biden’s Twitter feed said Russia "rakes in tens of billions of dollars" from the sale of its gold, its second largest export after energy.

On Saturday, Russia also launched dozens of missiles on several areas across the country far from the heart of the eastern battles. Some of the missiles were fired from Russian long-range Tu-22 bombers deployed from Belarus for the first time, Ukraine’s air command said.

The bombardment preceded a meeting between Russian President Vladimir Putin and Belarusian President Alexander Lukashenko, during which Putin announced that Russia planned to supply Belarus with the Iskander-M missile system.

Russian Defense Ministry spokesperson Igor Konashenkov said late Saturday that Russian and Moscow-backed separatist forces now control Severodonetsk and the villages surrounding it. He said the attempt by Ukrainian forces to turn the Azot plant into a "stubborn center of resistance" had been thwarted.

Haidai confirmed Saturday that Severodonetsk had fallen to Russian and separatist fighters, who he said were now trying to blockade Lysychansk from the south.

Russia’s Interfax news agency quoted a spokesperson for the separatist forces, Andrei Marochko, as saying Russian troops and separatist fighters had entered Lysychansk and that fighting was taking place in the heart of the city. There was no immediate comment on the claim from the Ukrainian side.

Lysychansk and Severodonetsk have been the focal point of a Russian offensive aimed at capturing all of Donbass and destroying the Ukrainian military defending it – the most capable and battle-hardened segment of the country’s armed forces.

Capturing Lysychansk would give Russian forces control of every major settlement in the province, a significant step toward Russia’s aim of capturing the entire Donbass. The Russians and separatists control about half of Donetsk, the second province in the Donbass.