Russia attacked Ukraine’s capital early on Monday with Iranian-made drones, continuing its campaign of lethal strikes against Ukrainian energy infrastructure and civilian targets even as it faces significant setbacks on the battlefield.

At least four people were killed in Kyiv, the capital, where the buzzing sound of the drones was followed by explosions. The attacks came during morning rush hour, one week after Moscow unleashed a missile barrage across the country that left at least 19 people dead. While Monday’s strikes were less deadly, they again struck fear into Ukrainians far from the front lines and signaled Russia’s aim of crippling power and other key services as winter looms.

A separate attack in the northeastern region of Sumy killed at least three people on Monday, the regional governor said, when Russian missiles struck an infrastructure target.

The strikes in the capital highlighted Russia’s growing use of the Iranian-made drones known as “kamikazes,” which explode on impact and are easier to shoot down, as Western analysts say Moscow’s stocks of precision missiles are running low. While Iran has officially denied supplying Russia with drones for use in Ukraine, U.S. officials said that the first batch of such weapons was delivered in August. Ukraine’s Air Force said that Russia had fired 43 of the drones on Monday, but 37 were shot down by air defense systems.

Vitaly Klitschko, the mayor of Kyiv, said that 28 drones were spotted over the city, resulting in five strikes. Ukraine’s Air Force scrambled jets to chase and shoot the drones, while some were shot down by Ukrainian troops who fired into the air. The targets included the headquarters of Ukraine’s national energy utility and a municipal heating station.

Mr. Klitschko said at least four people were killed in the strikes in Kyiv. Among the dead were a young couple, including a woman who was six months pregnant, pulled from the wreckage of a residential building, Mr. Klitschko said.

Serhiy Kruk, head of the State Emergency Service of Ukraine, said 18 people were wounded, including two rescue workers who were responding to an initial strike when a second hit in the same area.

Mykhailo Podolyak, an adviser to President Volodymyr Zelensky of Ukraine, condemned Iran, saying it was “responsible for the murders of Ukrainians.”

Russia’s Defense Ministry said in a statement that its forces had used “high-precision air- and sea-based weapons” to attack military targets and energy infrastructure in Ukraine. The ministry said it had hit “all designated targets,” without elaborating.

Outside a four-story building that was hit, emergency workers recovered the body of a woman from the collapsed walls. An investigator held her thin wrist, covered in dirt and debris, and then folded her arms across her chest as her body was placed in a bag.

In the attack on the municipal heating station, a drone struck near where another had hit about an hour earlier, on opposite sides of Zhylianska Street. It appeared to be what Ukrainians call a “double-tap attack,” a tactic that aims to kill emergency workers or firefighters responding to an initial strike.

In southern Ukraine, a Russian strike damaged an electrical substation, again cutting power to the Zaporizhzhia Nuclear Power Plant, officials said on Monday. The plant’s backup diesel generators switched on, according to a statement from the Ukrainian nuclear energy company, Energoatom.

And in Vinnytsia, in central Ukraine, a strike hit a piece of critical infrastructure, the regional governor said, without providing details.

Monday’s attacks highlighted the vulnerability of Ukraine’s energy infrastructure. While the government has swiftly moved to repair the damage from last week’s attacks, the country has seen rolling blackouts, and officials have called on Ukrainians to reduce their electricity consumption.

Moscow has escalated its aerial bombardment after an explosion this month partially damaged the bridge linking Russia to Crimea, the peninsula that Moscow illegally annexed from Ukraine in 2014. But Russia’s ground forces continue to face setbacks on the battlefield in eastern and southern Ukraine, although Russian troops were attacking along part of the front in the eastern Donbas region on Sunday, the Ukrainian military said.