Multiple explosions were heard near the main airport in the Ukrainian capital of Kyiv soon after Russia announced a military operation in Ukraine, media reports said on Thursday.
Russian President Vladimir Putin announced a special 'military operation' to protect Donbas, the separatist-held region in eastern Ukraine, on Thursday.
Media reports indicate several explosions in the Boryspil area to the east of the capital Kyiv.
According to CNN, at least two massive explosions were reported in the early hours of Thursday.
Meanwhile, the General Staff of the Ukrainian Armed Forces have claimed to have shot down five Russian aircraft and a helicopter, media reports said.
However, the Russian military has denied the claims, the TASS news agency reported.
'Message from the General Staff of the Armed Forces of Ukraine ... 5 planes and a helicopter of the aggressors were shot down in the area of the Armed Forces today,' the Defence of Ukraine said in a tweet in Ukrainian.
Putin warns against 'any interference'
Putin warned other countries that any attempt to interfere with the Russian action would lead to 'consequences'.
Delivering an emergency address, Putin said the operation has been launched to demilitarise Ukraine and defend people 'suffering persecution and genocide' by the Kyiv regime.
"I have taken the decision to carry out a special military operation. Its goal will be to defend people who for eight years are suffering persecution and genocide by the Kyiv regime. For this we will aim for demilitarisation and de-Nazification of Ukraine," said Putin, asking Ukrainian soldiers to lay down arms.
"Anyone who tries to interfere with us, or even more so, to create threats for our country and our people, must know that Russia's response will be immediate and will lead you to such consequences as you have never before experienced in your history," he added.
'No threat to civilians'
Meanwhile, The Russian Defence Ministry has ruled out any threat to Ukrainian civilians as it carries out military operations in the country, local media reported.
Russia has clarified that its army is not carrying out any missile, aviation or artillery strikes on the cities of Ukraine and is not targeting civilians, Sputnik News reported.
"Military infrastructure, air defense facilities, military airfields, aviation of the Armed Forces of Ukraine are being put out of action by [Russia's] high-precision means of destruction," the news agency quoted the ministry as saying.
The ministry added that the military action does not threaten the Ukrainian civilian population.
Calls for peace ignored
The attack comes hours after Ukrainian President Volodymyr Zelenskyy said Ukraine has not posed and will not pose a threat to Russia.
In an emotional appeal delivered largely in Russian, Zelenskyy said, "You are being told that Ukraine can pose a threat to Russia."
"It was not like this in the past, it is not like this now and it will not be so in the future. You demand security guarantees from NATO. We also demand guarantees of our security -- from you, from Russia, and other guarantors of the Budapest memorandum," Zelenskyy said in a video address.
Ukrainian President also refuted Moscow's claims that his country poses a threat to Russia and warned that a Russian invasion would cost tens of thousands of lives.
After the military operation was announced, US President Joe Biden condemned Russia's actions, in the Donbas region of eastern Ukraine.
The US President said that he is monitoring the situation from the White House, and will soon meet with the other G7 leaders.
Earlier, the White House had warned Putin of significant consequences if Moscow invaded Ukraine.