The Russian military blasted Ukraine’s capital, Kyiv, with waves of ballistic missiles and drones that lasted into Thursday morning, a deadly show of force after weeks of Ukrainian attacks in Russia that have heaped pressure on President Vladimir V. Putin.

At least 21 people were killed and 85 injured in overnight attacks, Ukrainian officials said, as firefighters raced to extinguish blazes in districts across the city. Several apartment buildings were partially destroyed and an unknown number of people were trapped in the rubble, according to the local authorities.

The barrage was the latest in the deadliest spring for civilians in Ukraine since the opening months of Moscow’s full-scale invasion in 2022, with the violence increasing as both sides have raced to develop new weapons.

Russia has been bombarding Ukrainian towns and cities throughout the war, but Ukraine is increasingly able to bring the war further into Russia. It is using its growing arsenal of domestically produced long-range drones and cruise missiles to attack fuel facilities and military installations deep inside the country. And it is systematically hitting targets in every corner of occupied Ukraine, including Crimea, a peninsula controlled by Russia.

Kyiv’s growing reach has caused logistical struggles for the Russian military and has led to widespread fuel shortages across the country, eroding Mr. Putin’s ability to insulate large parts of Russia, including Moscow, the capital, from the war. But it does not seem to have dented his resolve to continue fighting.

After initially staying silent on Ukraine’s ratcheting up of attacks, Mr. Putin told Russian state television on Sunday that the assaults on critical infrastructure were “obviously creating problems” and “certain shortages,” though he said the situation was not “critical.”

Russia’s defense ministry said in a statement on Thursday that the strikes on Kyiv were in response to Ukraine’s recent attacks. Ukraine’s foreign minister, Andrii Sybiha, said that it was wrong to equate his country’s strikes in Russia with Moscow’s unrelenting bombardments.

“It is immoral to justify Russian atrocities against Ukrainians by saying that Moscow acts in response to Ukraine’s long-range strikes against Russia,” he said on social media. “In this war, there is an aggressor and a country defending itself under Article 51 of the U.N. Charter. ”

The Ukrainian military said it had targeted Russian energy infrastructure again on Thursday, claiming that it had struck an oil refinery in the town of Kstovo in Nizhny Novgorod region, one of the largest in Russia.

The European Union responded to Russia’s attacks by proposing to impose new economic sanctions against entities that support Moscow’s military defense industry.

“Words of condemnation alone will not stop attacks on Kyiv,” Kaja Kallas, the bloc’s top diplomat, said on social media. “Only sustained military support for Ukraine and increased pressure on Moscow can do that.”

Ukraine has been trying to force the Russian military to pay a heavy price for every mile of land it seizes and increase the economic costs for the Kremlin. Moscow believes its military can outlast Kyiv’s outnumbered forces on the front while inflicting such a heavy human and economic toll that it breaks the will of civilians, according to Western military analysts.

Many of Kyiv’s three million residents had been bracing for a large-scale Russian assault in part because about two weeks had passed since the last one, giving Moscow time to stockpile missiles and drones. President Volodymyr Zelensky of Ukraine had warned in recent days that Russia was preparing a “massive strike,” and he urged people to be “especially careful.”

Before dawn on Thursday, explosions boomed and thick smoke rose over the Ukrainian capital. More than 50,000 people sought shelter in the city’s subway stations, according to the local authorities, and tens of thousands took cover in basements, garages or in makeshift shelters at home.

Firefighters and emergency workers raced to extinguish blazes across the city. Several apartment buildings were partially destroyed and an unknown number of people were trapped in the rubble, according to the local authorities.

Mr. Zelensky said more than 30 locations across Kyiv were hit or damaged, including residential buildings, an ambulance station, and a research institute.

In an underground parking garage in the Darnytsia district of the city, dozens of residents waited out the night’s bombardment. Some slept in their cars, others on the concrete floor.

“We could hear the explosions clearly — it wasn’t far away,” said Olena Rudenkova, a resident of the district. What has changed, she added, was not the fear but the response to it. “I don’t think anyone cries anymore, not even the children,” she said. “Everyone becomes as focused and angry as possible.”

The Ukrainian Air Force said Russia launched 74 missiles and 476 drones in the attack, primarily targeting Kyiv. The barrage included 28 ballistic missiles, which can only be intercepted by Patriot systems, it added.

Ukraine’s stockpile of Patriot interceptors was running low even before the latest attacks. NATO countries have been regularly shipping modest numbers of the interceptor missiles to Kyiv, but the Ukrainian military has been unable to keep up with Russia’s frequent strikes or Moscow’s capacity to produce new missiles.