MOSCOW — At least four people were killed by Ukrainian drone strikes across Russia, including in Moscow, on Sunday in the biggest attack by Ukraine this year and one of its largest of the war, according to the local authorities and Tass, the Russian state-owned news agency.

Russia’s Ministry of Defense said 556 Ukrainian drones had been intercepted or shot down in more than a dozen regions, according to the local authorities and Tass. President Volodymyr Zelenskyy of Ukraine said that the attacks on the Moscow region were an “entirely justified” response to Russia’s attacks on Ukrainian cities.

“We are clearly telling the Russians: their state must end its war,” he wrote on social media.

Three people were killed and 12 were injured when drones struck residential buildings in the Moscow suburbs of Khimki and Mytishchi, according to Andrei Vorobyov, the regional governor. India’s Embassy said that one Indian citizen was killed in the Moscow region, and that three others were wounded. Strikes also damaged homes and apartment complexes in four other towns, he said, the latest sign that the war is hitting increasingly close to the heart of power in Russia.

In the Moscow suburb of Zelenograd, two drones or remnants of them damaged the lower floors of a residential complex. On Sunday afternoon, workers were removing furniture from the damaged apartments as local residents gathered around the building to gape. As they sat watching construction workers try to repair the building’s facade, residents discussed a new type of home insurance against drones.

Drops of blood from people injured by shards of glass were smeared in the stairwell of the building. One resident, Maria, said people in the neighborhood had gotten used to drones flying overhead toward Moscow. She had taped up her windows in case of an attack.

Her young teenage son, who had been home alone, heard the first strike and called her from the bathroom before the second explosion hit. She said she was disappointed that the emergency services had not arrived faster to help care for her son, who had been standing alone in the cold after fleeing the building.

“It’s the fifth year of the war, you would have thought they would be better prepared by now,” said Maria, 44, who did not want to give her full name out of fear of retribution.

This month, drones struck an upscale residential apartment building a few miles from the Kremlin, as Ukraine intensifies its campaign of long-range attacks deep inside Russia.

Zelenskyy had vowed to increase the range and scale of those attacks after a Russian assault on Kyiv, Ukraine, killed 24 people last week. On Saturday, he shared a video of what he said were long-range Ukrainian strikes carried out over the past week and warned that “most of the operations are still ongoing.”

Ukraine’s Security Service said it had targeted a plant, a refinery and two oil-pumping stations in the Moscow region. It also said strikes hit military “infrastructure and air-defense” systems at an airfield in Russian-occupied Crimea. Those claims could not be independently confirmed.

Sergei S. Sobyanin, the mayor of Moscow, said drones had struck a checkpoint near the Moscow Oil Refinery on Sunday, injuring construction workers. The refinery’s operations were not disrupted, he said.