Ukrainian president Volodymyr Zelensky called on citizens to defend the nation as his Interior Ministry reported that there have been hundreds of casualties since Russia began its nationwide assault early Thursday morning.

“We are issuing arms to all those capable of defending our sovereignty,” Zelensky said during a televised address from Kyiv, in a translation broadcast on CNN. “Each citizen of Ukraine will decide the future of our people. Anyone with military experience who is able to join the defense of Ukraine must report to call-up stations.”

Zelensky added that Ukraine will not “cede its freedom.”

“Whatever they might think in Moscow, to Ukrainians independence and the right to live on our land is the highest value,” Zelensky said. “Russia has attacked our state in a cunning way, in the way Nazi Germany did during the Second World War.”

Zelensky: We have severed diplomatic relations with Russia… Russia has attacked our state in the way Nazi Germany did during the Second World War.. From today, our countries are on opposing sides of world history.. pic.twitter.com/p6Ixjc2T9p

— Acyn (@Acyn) February 24, 2022

Zelensky’s statement was issued hours after Russia began shelling virtually every major Ukrainian population center, including the capital city of Kyiv; Kharkiv, the second-largest city in Ukraine, which sits just 20 miles from the Russian border; and Odessa, the strategically valuable southern port city. The aerial bombardment was swiftly followed by a ground incursion featuring Russian tanks and armored personnel carriers streaming through multiple checkpoints on the Russian-Ukrainian border.

Zelensky adviser Oleksiy Arestovich confirmed that over 40 Ukrainian soldiers were killed on Thursday morning, with dozens more wounded in the initial hours of the invasion. However, the Ukrainian Interior Ministry said there are already hundreds of casualties, however it was not immediately clear how many of the casualties were fatalities, according to CNN.

Footage of burned apartment buildings in the city of Kharkiv showed potential evidence of Russian attacks on civilian targets, the New York Times reported.

KHARKIV, UKRAINE – FEBRUARY 24: (EDITORS NOTE: Image depicts graphic content) A wounded woman is seen as airstrike damages an apartment complex outside of Kharkiv, Ukraine on February 24, 2022. (Photo by Stringer/Anadolu Agency via Getty Images) pic.twitter.com/FxXoLEN3sQ

— Kevin Baron (@DefenseBaron) February 24, 2022

Meanwhile, a Russian artillery barrage aimed toward Ukraine was captured live on air by CNN:

🚨BREAKING: Russia fires artillery rockets toward Ukraine live on the air on CNN with @fpleitgenCNN reporting pic.twitter.com/C4eceHQ8rx

— Nora Neus (@noraneus) February 24, 2022

Washington Post reporter Isabelle Khurshudyan wrote on Twitter that she and her colleagues heard the blasts from Kharkiv, 45 minutes from the Russian border.

The booms are pretty distant right now, but Kharkiv is only 45 mins from Russia-Ukraine border. https://t.co/JqV5i0ai5J

— Isabelle Khurshudyan (@ikhurshudyan) February 24, 2022

A group of people gathered in Kharkiv to pray in the middle of the street, in footage captured by CNN:

CNN witnesses a small group of Ukrainians in Kharkiv gathering and kneeling in prayer.
"So, to see these people kneeling on the cold stone in prayer is
honestly — it's very moving," Clarissa Ward.#PrayForUkraine pic.twitter.com/47NgqwbXxA

— Nicholas Fondacaro 🇺🇦 (@NickFondacaro) February 24, 2022

Ukrainians lined up at banks to retrieve valuables on Thursday, including in Lviv in the west of the country.

“They sent us a message and said come collect all your valuable today, tomorrow we will be closed,” Christina Kornienko told the Times. Kornienko said she thought the most likely scenario would be that “the women will go to Poland, and the men will fight.”

Air raid sirens sounded earlier in the morning in Lviv, where U.S. diplomatic had moved recently for fear of being caught in the crossfire nearer to the Russian border in Kyiv.. American staff are now working out of Poland.

Air Raid sirens begin in Lviv, Ukraine pic.twitter.com/lIGgTfKVmU

— Lucas Tomlinson (@LucasFoxNews) February 24, 2022

Russia has attacked major cities across Ukraine from the air while Russian troops entered the country from the east and from northern neighbor Belarus. Ukrainian authorities confirmed that Russian helicopters attacked the Antonov Airport, an international cargo airport near the capital of Kyiv, Buzzfeed News reported:

Confirmed by Ukrainian authorities. A large air assault operation with Mi-8 helicopters on Antonov International Airport in Hostomel. Interior Ministry says Russia has seized control. Very dangerous; it's just 15 minutes west of the capital ring road. pic.twitter.com/JhlyVktVRC

— Christopher Miller (@ChristopherJM) February 24, 2022

Russian president Vladimir Putin announced early Thursday morning local time that his government has resolved “to launch a special military operation” aimed at the “demilitarization and denazification of Ukraine,” heralding the start of a land war on the European continent.

Threatening those who might oppose his efforts to either outright annex parts of Ukraine, or install Ukrainian leaders with pro-Russian bents, Putin warned that "those who would be tempted to intervene . . . will have consequences that you never have had before in your history."

Putin’s address has been followed by reports of explosions across Ukraine, including in its capital city of Kyiv. After Putin’s speech, the Ukrainian interior minister, Anton Gerashchenko, confirmed to CNN that “the invasion has begun.”

Per NBC’s Susan Kroll, Gerashchenko has also confirmed that Russian troops have landed in the Ukrainian port city of Odessa, the third-largest urban center in the country. Ukrainian military sources have disputed a Russian presence in Odessa, according to Reuters, however, providing an early example of the fog of war that is likely to cloud the conflict.

Kyiv mayor Vitaly Klichko issued the following statement responding to the evolving situation:

“In Kyiv we can hear noise of shelling. The worst enemy now is panic. Keep calm. Everyone not involved in critical city functions, stay home. We have to prevail.”

Air raid sirens sound in Kyiv after Russian Pres. Vladimir Putin announced a military operation in Ukraine. https://t.co/mSLyAPWJRI pic.twitter.com/OPjSrwlJWt

— ABC News (@ABC) February 24, 2022

CNN has reported that Russian missile strikes have targeted Vasilkovsky airfield near Kyiv in an effort to destroy Ukraine’s air defenses ahead of the forthcoming ground invasion, and various outlets have reported that commercial airports — including Kyiv’s Boryspil International Airport — have also come under fire.

CNN has also reported that Belarus has mobilized its forces to assist Russia. Video from Ukraine’s Belarussian border shows tanks entering the country.

NOW: Ukrainian Border Guard video, obtained by CNN, shows military tanks rolling into Ukraine from Belarus which borders Ukraine in the north. pic.twitter.com/aTrzvjylB1

— David Begnaud (@DavidBegnaud) February 24, 2022

In an address delivered prior to Putin’s, Ukrainian president Zelensky declared that “the government of Ukraine wants peace. It’s doing everything it can. We’re not alone. That’s true, lots of countries support Ukraine. Because this isn’t about peace at any price. It’s about peace, principles, justice, international law, the right to determine your own future.”

After Putin’s announcement and the commencement of military operations, Zelensky delivered another speech noting that he had spoken with President Joe Biden and urging the Ukrainian people to “stay strong.”

“We will win because we are Ukraine. Glory to Ukraine,” he added.

Reuters is reporting that the Ukrainian military has shot down five Russian planes and one helicopter in the easternmost Ukrainian region of Luhansk. In a separate statement, Zelensky revealed that he has ordered the Ukrainian military "to inflict maximum losses" on the invading Russian forces.

The White House released a statement following Putin’s de facto declaration of war asserting that “the prayers of the entire world are with the people of Ukraine tonight as they suffer an unprovoked and unjustified attack by Russian military forces.”

“Russia alone is responsible for the death and destruction this attack will bring, and the United States and its Allies and partners will respond in a united and decisive way,” it continued.

On Fox News, Alexey Goncharenko, a member of Ukraine’s parliament, implored the United States to find a way to end the conflict, saying “it [Russia] should be stopped now, because they’re killing innocent people just in this minute.” Goncharenko asked that the American government enforce a no-fly zone over his country, explaining his country’s need for “help in the skies,” while acknowledging that America could not contribute ground troops to the conflict. “We are ready to fight for ourselves. We’re a proud nation and strong nation,” said Goncharenko.

Even as the Russian military began its attack on Thursday evening, the crisis was being discussed at the United Nations, where Russia currently serves as the rotating chair of the Security Council. “There is no purgatory for war criminals. They go straight to hell,” said Ukraine’s ambassador to the body.

Fox News national security correspondent Jennifer Griffin has reported that a U.S. official has told her that “right now we are seeing the pre assault fires. Expect this to go on for a few hours. Land attack to follow with ALL of the full forces Putin has arrayed. Explosions heard in Kiev, Odessa, Mariupol. ‘It's begun.'”

Putin’s address was the culmination of a months-long Russian military build-up on the Ukrainian border. His speech on Thursday indicated an intention to conduct a broader incursion than the “peacekeeping” operation he had previously announced in the regions he had recognized as independent, and potentially even an effort to take the entirety of the Ukraine.