KYIV : Ukraine's capital was subjected to the largest drone attack since the start of Russia's war, local officials said, as Kyiv prepared to mark the anniversary of its founding on Sunday. At least one person was killed.

Russia launched the “most massive attack” on the city overnight Saturday with Iranian-made Shahed drones, said Serhii Popko, a senior Kyiv military official. The attack lasted more than five hours, with air defense reportedly shooting down more than 40 drones.

A 41-year-old man was killed and a 35-year-old woman was hospitalized when debris fell on a seven-story nonresidential building and started a fire, Kyiv Mayor Vitali Klitschko said.

Ukraine’s air force said that Saturday night was also record-breaking in terms of Shahed drone attacks across the country. Of the 54 drones launched, 52 were shot down by air defense systems.

In the northeastern Kharkiv province, regional Gov. Oleh Syniehubov said a 61-year-old woman and a 60-year-old man were killed in two separate shelling attacks.

Kyiv Day marks the anniversary of Kyiv’s official founding. The day is usually celebrated with live concerts, street fairs, exhibitions and fireworks. Scaled-back festivities were planned for this year, the city’s 1,541st anniversary.

The timing of the drone attacks was likely not coincidental, Ukrainian officials said. “The history of Ukraine is a long-standing irritant for the insecure Russians,” Ukraine's chief presidential aide, Andriy Yermak, said on Telegram.

“Today, the enemy decided to ‘congratulate’ the people of Kyiv on Kyiv Day with the help of their deadly UAVs (unmanned aerial vehicles),” Popko also wrote on the messaging app.

Local officials in Russia’s southern Krasnodar region said that air defense systems destroyed several drones as they approached the Ilsky oil refinery.

Russia’s southern Belgorod region, bordering Ukraine, also came under attack from Ukrainian forces on Saturday, local officials said. Regional Gov. Vyacheslav Gladkov reported Sunday that a 15-year-old girl and a 17-year-old boy were wounded in the shelling.

Drone attacks against Russian border regions have been a regular occurrence since the start of the invasion in February 2022, with attacks increasing last month. Earlier this month, an oil refinery in Krasnodar was attacked by drones on two straight days.

Ukrainian air defenses, bolstered by sophisticated Western-supplied systems, have been adept at thwarting Russian air attacks — both drones and aircraft missiles.

Earlier in May, Ukraine prevented an intense Russian air attack on Kyiv, shooting down all missiles aimed at the capital. The bombardment, which additionally targeted locations across Ukraine, included six Russian Kinzhal aero-ballistic hypersonic missiles, repeatedly touted by Russian President Vladimir Putin as providing a key strategic competitive advantage and among the most advanced weapons in his country’s arsenal.

Sophisticated Western air defense systems, including American-made Patriot missiles, have helped spare Kyiv from the kind of destruction witnessed along the main front line in the country’s east and south. While most of the ground fighting is stalemated along that front line, both sides are targeting other territory with long-range weapons.

Against the backdrop of Saturday night’s drone attacks, Russia's ambassador to the U.K., Andrei Kelin, warned of an escalation in Ukraine. He told the BBC on Sunday his country had “enormous resources” and it was yet to “act very seriously,” cautioning that Western supplies of weapons to Ukraine risked escalating the war to a “new dimension.” The length of the conflict, he said, “depends on the efforts in escalation of war that is being undertaken by NATO countries, especially by the U.K.”

Kelin’s comments are typical of Russian officials’ rhetoric with regard to Moscow's military might, but contradict regular reports from the battlefield of Russian troops being poorly equipped and trained.

Also on Sunday, the death toll from Friday’s missile attack on the central Ukrainian city of Dnipro, the regional capital of the Dnipropetrovsk province, rose to four. Regional. Gov. Serhii Lysak said that three people who were considered missing were confirmed dead. There were 32 people, including two children, wounded in the attack, which struck a building containing psychology and veterinary clinics.