NATO raised fighter jets

"In the southeastern part of the country, an increased level of noise may appear as Polish and allied aircraft have begun to fly in the airspace," the command's statement reads.

It is stated that "the long-range aviation of the Russian Federation has again launched missile attacks on Ukraine", which is why "all necessary procedures have been initiated to ensure the safety of Polish airspace".

"The operational command of the Armed Forces is constantly monitoring the situation and is ready to immediately respond to threats," the statement added.

Poland has regularly published such messages in recent months, and the timing of their publication usually coincides with an air strike warning in Ukraine.

At the same time, some Ukrainian media reported that explosions could be heard in Kyiv after the sounding of the air danger siren. After the explosions, according to the media, columns of smoke were seen in several places.

Regarding the whole situation, the energy company DTEK announced on its Telegram channel that three substations were destroyed or damaged.

"Kyiv. Three substations of DTEK have been completely destroyed or damaged. The electrical network has also been damaged. Workers have already gone to the field," according to Telegram on the DTEK channel.

• Fierce attack on Kyiv; Hospital under attack; Thick smoke over the city PHOTO/VIDEO