Invading Russian forces pressed deep into Ukraine as deadly battles reached the outskirts of Kyiv and the West responded with punishing sanctions.
Russian missiles and shelling rained down on Ukrainian cities Thursday after President Vladimir Putin unleashed a full-scale ground invasion and air assault, forcing civilians to shelter on metro systems, with 100,000 people displaced.
Across Ukraine, at least 137 "heroes" were killed after the first day of fighting, President Volodymyr Zelensky said, calling up conscripts and reservists nationwide to fight in a general mobilisation.
The United States moved to impose sanctions on Russian elites and banks, but stressed that US forces would not head to eastern Europe to fight in Ukraine, but would instead defend "every inch" of NATO territory.
Zelensky said there was now a "new iron curtain" between Russia and the rest of the world, like in the Cold War, adding in a later speech that his nation had been "left alone".
"Who is ready to fight alongside us? I don't see anyone."
Ukraine said Russian forces had seized the Chernobyl nuclear power plant, an area still heavily contaminated with radioactive material after a devastating 1986 accident, prompting the IAEA nuclear watchdog to call for "restraint".
Witnesses told AFP that Russian paratroopers wrested control of the strategic Gostomel airfield, on the northwestern outskirts of Kyiv, after swooping in with helicopters and jets from the direction of Belarus.
"The helicopters came in and then the battles started. They were firing machine guns, grenade launchers," resident Sergiy Storozhuk said.
- 'Better to die' -
Western intelligence has said that Russia is seeking to mass "overwhelming force" around the Ukrainian capital and that Moscow has established "complete air superiority" over Ukraine.
Elsewhere, Russian ground forces moved into Ukraine from the north, south and east, forcing many Ukrainians to flee their homes as the sound of bombing reverberated.
Moscow's defence ministry said its forces had "successfully completed" their objectives for the day, earlier claiming to have destroyed over 70 Ukrainian military targets, including 11 airfields.
Olena Kurilo was among 20 people wounded by flying shards of glass following a blast in the eastern Ukrainian town of Chuguiv.
"Never, under any conditions will I submit to Putin. It is better to die," the 52-year-old teacher said, her face covered in bandages.
US President Joe Biden announced export controls against Russia to cut off more than half of the country's high-tech imports, alongside sanctions on Russian elites he called "corrupt billionaires", and banks.
He earlier said the G7 group of wealthy nations had agreed to impose "devastating" economic sanctions.
The EU moved to impose "massive" sanctions on Russia's energy and finance sectors, while French President Emmanuel Macron called Putin to "demand immediate halt" to the offensive.
Biden once again said additional US forces were not heading to eastern Europe to fight in Ukraine, but would defend "every inch" of NATO territory.
- 'War on all of Europe' -
Weeks of diplomacy failed to deter Putin, who massed over 150,000 troops on Ukraine's borders in what the West said was Europe's biggest military build-up since World War II.
Zelensky called the attack on Chernobyl "a declaration of war on all of Europe" while 18 people were killed at a military base near the Black Sea port of Odessa in the deadliest single strike reported by Kyiv.
The Ukrainian capital declared an overnight curfew but said underground stations would remain open throughout to serve as bomb shelters.
Ukraine also said a military plane with 14 people on board crashed south of Kyiv and that officials were determining how many people died, while a transport plane crashed in Russia killing the crew.
Ukrainian forces said they had killed "around 50 Russian occupiers" while repulsing an attack on a town on the frontline with Moscow-backed rebels, which could not immediately be confirmed by AFP.
In the Ukrainian village of Starognativka near the frontline where separatists have faced off against Kyiv's forces, official Vladimir Vesyelkin said missiles had rained down since the morning and power was out.
"They are trying to wipe the village off the face of the earth," he said.
The fighting spooked global financial markets, with stocks plunging and oil prices soaring past $100.
IMF chief Kristalina Georgieva said the unrest carried "significant economic risk" for the world, but Putin insisted he did not seek to undermine the global economic system.
- Demonstrations across Europe -
In a televised address, Putin justified the assault as a defence of the self-proclaimed Donetsk and Lugansk republics in eastern Ukraine.
The Kremlin earlier said the leaders of the two separatist territories had asked Moscow for military help against Kyiv after Putin recognised their independence on Monday.
A conflict between the separatists and government forces has dragged on since 2014, killing more than 14,000 people on both sides.
NATO said it had activated "defence plans" for allied countries but alliance chief Jens Stoltenberg said there was no plan to send NATO forces into Ukraine.
Russia has long demanded that Ukraine be forbidden from ever joining NATO and that US troops pull out from Eastern Europe.
In the Baltics, Lithuania declared a national emergency and Latvia banned three Russian TV channels that were broadcasting in the country, saying they posed a "threat to national security". The two along with the Czech Republic, also stopped issuing visas to Russians.
Demonstrators took to the streets of European capitals to condemn Russia but a small anti-war protest in Moscow was quickly shut down by police. Monitors said over 1,700 people were detained at protests across the country.
The first Ukraine refugees have begun to trickle into Hungary and Romania while the UN said 100,000 had been displaced by the fighting.
"Anyone who can is fleeing," said Krisztian Szavla, one of the first refugees who arrived in Hungary Thursday from Ukraine's western Transcarpathia region.