Four people have died after drones laden with explosives struck Kyiv, according to Ukrainian authorities.
It is the second Russian barrage in as many weeks, after months in which air attacks had become a rarity in Ukraine's capital.
Energy facilities were hit, while four people were killed when one drone largely collapsed a residential building.
Intense, sustained bursts of gunfire rang out as the Iranian-made Shahed drones buzzed overhead, apparently from soldiers trying to destroy them. Others headed for shelter as they nervously scanned the skies.
Previous Russian airstrikes on Kyiv were mostly with missiles.
Andrii Yermak, head of the presidential office, posted on social media that Shahed drones were used.
Analysts believe the slower-moving Shahed drones can be programmed to accurately hit certain targets using GPS – unless the system fails.
Watch: Iranian-supplied 'suicide drone' being used by Russians against Ukraine.
Ukraine has become grimly accustomed to attacks nearly eight months into the Russian invasion and city life resumed as rescuers picked through debris.
Mayor Vitali Klitschko said Monday's barrage came in successive waves of 28 drones — in what many fear could become a more common mode of attack as Russia seeks to avoid depleting its stockpiles of long-range precision missiles.
Five drones plunged into Kyiv itself, Prime Minister Denys Shmyhal said.
In the Kyiv region, at least 13 were shot down, all flying in from the south, according to the spokesman for Ukraine's air force, Yurii Ihnat.
One strike appeared to target the city's heating network, hitting an operations centre. Another slammed into a four-storey residential building, ripping open a gaping hole and collapsing at least three apartments on top of each other.
Four bodies were recovered, including those of a woman who was six months pregnant and her husband, Mr Klitschko said. An older woman and another man were also killed there.
Ukrainian foreign minister Dmytro Kuleba called for European Union sanctions on Iran for providing drones to Russia.
He reiterated Ukraine's need for air defences and ammunition, saying he had addressed a meeting of EU counterparts from a bomb shelter because air raid sirens were howling.
The European Union's top diplomat says the bloc is gathering evidence about Iran's alleged sale of drones to Russia and will respond if the allegations prove true.