Explosions were heard in the centre of the Ukrainian capital Kyiv early on Wednesday, the city's mayor says.
Vitali Klitschko said blasts rocked the central Shevchenkivskyi district and emergency services had been dispatched.
Air defence systems are at work, Kyiv Governor Oleksiy Kuleba says.
Reporters heard loud explosions shortly after the air raid siren sounded. Russia has repeatedly targeted Ukrainian energy infrastructure since October with missiles and drones.
President Volodymyr Zelensky said Ukrainian forces had shot down 13 Iranian-made Shahed drones, which he said amounted to all those launched by Russia early on Wednesday.
Kyiv city's military administration said a drone fragment had hit an administrative building in the city centre and four residential buildings. But a spokesperson for the city emergency services told Ukrainian media that no victims had been reported in the strike.
Kyiv governor Kuleba said: "The air defence system is operating. It's important now to stay in shelters and safe places. Russia is continuing its energy terror against our country. But we are getting stronger daily."
Ukraine has accused Iran of supplying Russia with "kamikaze" drones used in deadly attacks on 17 October, which Tehran initially denied.
Iran later admitted sending Moscow a limited number of drones "many months" before the war.
In response, Ukraine's President Volodymyr Zelensky said this was a lie and that many more Iranian drones were being used.
Russia has been targeting Ukraine's energy grid in recent months in a bid to demoralise its population.
Global leaders have said the strikes civilians infrastructure amount to a war crime, but last week Russian President Vladimir Putin defended the attacks and said they were in response to blast on the Russian bridge to annexed Crimea on 8 October.
The strikes come amid reports that the US is preparing to arm Ukraine with its state-of-the-art Patriot air defence system. Senior defence officials told the Reuters news agency that the announcement could come as soon as Thursday.
The system is among the most advanced in the world and is usually in short supply. Due to its long-range capability it could potentially shoot down Russian missiles and drones before they come within range of Ukrainian cities.
But unlike Ukraine's existing air defence systems, Patriot systems require large crews to operate them, and it could take several months to train Kyiv's forces to use it effectively.
Russia would likely view any attempt to arm Ukraine with Patriot defences as an escalation. Former president Dmitry Medvedev - who is now deputy chairman of the national security council - warned against the move last month.
Source: BBC
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