Missiles hit two residential buildings in Ukraine's capital Kyiv on Tuesday, in an attack blamed on Russia.

"Attack on the capital. According to preliminary information, two residential buildings were hit in the Pecherskyi district. Several missiles were shot down by air defense over Kyiv," the city's Mayor Vitali Klitschko said on Telegram.

Klitschko added that medics and rescue teams came to the scene of the residential buildings that were hit, adding that more details would be provided later.

Air raid alerts have been activated across Ukraine, including the capital Kyiv, guarding against possible Russian attacks, officials said on Tuesday.

Initial sirens were triggered in Ukraine's eastern and southern regions.

Lawmaker Oleksiy Goncharenko later said on Telegram that air raid sirens also blared in Kyiv, followed by announcements in the remaining regions.

There were no warnings reported in the Crimea region, which Russia illegally annexed in 2014.

Air raid alerts are sounded in Ukraine on an almost daily basis due to possible missile and drone strikes, which have targeted the country's civilian and energy infrastructure.​​​​​​​

The deputy head of the president's office Kyrylo Tymoshenko said in a statement online that the missiles had been fired by Russian forces.

He distributed footage of the apparent scene of the attacks, with a blaze emerging from a Soviet-era, five-story residential building.

"The danger has not passed. Stay in shelters," he added.

The Ukraine presidential chief of staff Andriy Yermak said the attack was a response to President Volodymyr Zelensky's address to the G20, during which he called on leaders to pressure the Kremlin to end its invasion.

"Does anyone seriously think that the Kremlin really wants peace? It wants obedience. But at the end of the day, terrorists always lose," Yermak said.

Russian forces have in recent weeks been targeting energy infrastructure across Ukraine and has launched barrages of missiles and sent swarms of drones on the capital.

Kyiv was last targeted by Russian forces nearly one month ago on Oct. 17.