Russia attacks Ukraine: Ukraine says about 40 killed so far

An adviser to Ukraine’s president says about 40 people have been killed so far in the Russian attack on the country.

Oleksii Arestovich, an adviser to President Volodymyr Zelenskyy said Thursday that several dozen people have been wounded.

He didn’t specify whether the casualties included civilians.

Zelenskyy said the Ukrainian authorities will hand weapons to all those willing to defend the country.

"The future of the Ukrainian people depends on every Ukrainian," he said, urging all those who can defend the country to come to the Interior Ministry’s assembly facilities.

RELATED: Ukraine Invasion: Russia claims to have knocked out Ukraine air defenses

In a televised address, Putin accused the U.S. and its allies of ignoring Russia’s demand to prevent Ukraine from joining NATO and offer Moscow security guarantees. He said Russia's goal was not to occupy Ukraine.

U.S. President Joe Biden denounced the "unprovoked and unjustified" attack on Ukraine and said the world will "hold Russia accountable."

Putin announced the military operation after the Kremlin said rebels in eastern Ukraine asked Russia for military assistance to help fend off Ukrainian "aggression." The announcement immediately fueled fears that Moscow was offering up a pretext for war, just as the West had warned.

A short time later, the Ukrainian president rejected Moscow’s claims that his country poses a threat to Russia and said a Russian invasion would cost tens of thousands of lives.

"The people of Ukraine and the government of Ukraine want peace," President Volodymyr Zelenskyy said in an emotional overnight address, speaking in Russian in a direct appeal to Russian citizens. "But if we come under attack, if we face an attempt to take away our country, our freedom, our lives and lives of our children, we will defend ourselves. When you attack us, you will see our faces, not our backs."

RELATED: Russia invades Ukraine: Biden responds to Putin's chilling threat not to ‘intervene

Dramatic and chilling video shows explosions lighting up the sky in Ukraine early Thursday morning as Russian military forces invaded the country.

The explosions were seen near Kharkiv, Ukraine, a city with a population of roughly 1.4 million nested near the eastern border and approximately 300 miles from the capital city of Kyiv, Ukraine.

The disturbing images come as Russian President Vladimir Putin announced a "special military operation" in the country while warning those who attempt to intervene would lead to "consequences they have never seen."

"I have a few words for those who could feel tempted to interfere with ongoing developments: whoever tries to impede us, let alone create threats for our country and its people must know that the Russian response will be immediate and lead to the consequences you have never seen in history," Putin said.

The Russian military announced early Thursday morning that it has knocked out Ukraine’s air defense assets and airbases, according to the Associated Press.

The Russian Defense Ministry said the Russian strikes have "suppressed air defense means of the Ukrainian military," adding that the infrastructure of Ukraine’s military bases has been incapacitated." It denied the claims that a Russian warplane was shot down over Ukraine.

Click here for the latest Central Florida news, Florida stories, and local headlines. 

Watch FOX 35 News for the latest updates.