Kyiv girds for assault, mayor says some Russians have entered

* Zelenskiy says he is Russia's 'number one target'* Britain says Russia failed to meet first day objectives* 'The kids...were crying and asking 'Mom, will we all die?'Russian missiles pounded Kyiv on Friday, families cowered in shelters and authorities told residents to prepare Molotov cocktails to defend Ukraine's capital from an assault that the mayor said had already begun with saboteurs in the city.Moscow claimed to have captured the Hostomel airfield northwest of the capital, a vital staging post for a planned assault on Kyiv, which has been fought over since the first hours of the war. This could not immediately be confirmed and the Ukrainian authorities reported heavy fighting there."The city has gone into a defensive phase. Shots and explosions are ringing out in some neighbourhoods. Saboteurs have already entered Kyiv," said Kyiv's mayor, former world heavyweight boxing champion Vitali Klitchko. "The enemy wants to put the capital on its knees and destroy us."Air raid sirens wailed over the capital of three million people, where some residents sheltered in underground metro stations, a day after Russian President Vladimir Putin launched an invasion that has shocked the world.Ukrainian officials said a Russian aircraft had been shot down and crashed into a building in Kyiv overnight, setting it ablaze and injuring eight people.President Volodymyr Zelenskiy tweeted that there had been heavy fighting with people killed at the entrance to the eastern cities of Chernihiv and Melitopol, as well as at Hostomel.Windows were blasted out of a 10-storey apartment block near Kyiv's main airport, where a two-metre crater filled with rubble showed where a shell had struck before dawn."How we can live through it in our time?... Putin should burn in hell along with his whole family," said Oxana Gulenko, sweeping broken glass from her room.Hundreds of people were crowded into a cramped bomb shelter beneath a building after a televised warning of air strikes."We don't know how long we have to stay here. Good we have chairs at least," said Viktoria, 35, while her kids of 5 and 7 slept without taking off their winter coats. "We're shocked... How can you wage a war against peaceful people?"Alla, 40 said: "The kids were scared, they were crying and asking 'Mom, will we all die?'"Witnesses said loud explosions could also be heard in Kharkiv, Ukraine's second-biggest city, close to Russia's border, and air raid sirens sounded over Lviv in the west. Authorities reported heavy fighting in the eastern city of Sumy.'NUMBER ONE TARGET'U.S. officials believe Russia's initial aim is to topple Zelenskiy and "decapitate" his government. Zelenskiy said he knew he was "the number one target" but he would stay in Kyiv.An adviser to Zelenskiy said Ukraine was prepared for talks with Russia, including on staying neutral, one of Moscow's pre-war demands. But Russian Foreign Minister Sergei Lavrov called that offer a lie and said no talks could be held until the Ukrainian military lays down its arms.Putin says Ukraine is an illegitimate state carved out of Russia, a view Ukrainians see as aimed at erasing their more than thousand-year history.Putin says he does not plan a military occupation, only to disarm Ukraine and remove its leaders. But it is not clear how a pro-Russian leader could be installed unless troops control much of the country. Russia has floated no name of such a figure.After Moscow denied for months it was planning an invasion, news that Putin had ordered one has shocked Russians accustomed to viewing their ruler of 22 years as a cautious strategist. Many Russians have friends and family in Ukraine.Russian state media have relentlessly characterised Ukraine as a threat, but thousands of Russians protested on Thursday against the war. Hundreds were swiftly arrested.One pop star posted a video on Instagram opposing the war, and the head of a Moscow state-run theatre quit, saying she would not take her salary from a murderer.Britain said Russia had failed to anticipate Ukrainian resistance to its plans to subdue their country."Contrary to great Russian claims - and indeed President Putin's sort of vision that somehow the Ukrainians would be liberated and would be flocking to his cause - he's got that completely wrong, and the Russian army has failed to deliver, on day one, its main objective," defence minister Ben Wallace said.Wallace said Russians had been pushed from the airport they had tried to take near Kyiv, making it harder to carry out their plan to attack the capital. They had also failed to break through Ukrainian lines near separatist enclaves in the east.Ukrainians were circulating an unverified recording on Friday of a Russian warship ordering a Ukrainian Black Sea outpost to surrender. The Ukrainians reply: "Russian warship, go fuck yourself." Zelenskiy said the 13 guards were killed by a Russian strike and would receive posthumous honours.Ukrainians were fleeing into neighbouring Poland, Romania, Hungary and Slovakia, mostly women and children after Kyiv restricted passage for men between 18 and 60 years old.Reuters journalists saw women crying as they bade goodbye to male loved ones and then crossed into northern Romania.Fuel, cash and medical supplies are running low in parts of Ukraine and this could drive as many as five million people to flee abroad, U.N. agencies said on Friday.A democratic nation of 44 million people, Ukraine voted for independence at the fall of the Soviet Union and has recently stepped up efforts to join NATO and the European Union, aspirations that infuriate Moscow.Western countries announced sweeping new sanctions on Russia, including blacklisting its banks and banning technology imports.But they stopped short of forcing Russia out of the SWIFT system for international bank payments, drawing criticism from Kyiv which says the most serious steps should be taken now. Germany and others use SWIFT to pay for Russian gas.Russia is one of the world's biggest energy producers, and both it and Ukraine are among the top exporters of grain. War and sanctions will disrupt economies around the world.Oil and grain prices have soared. Share markets around the world, many of which plunged on Thursday at news of the outbreak of war, were mainly rebounding on Friday.(Reporting by Natalia Zinets and Maria Tsvetkova in Kyiv, Aleksandar Vasovic in Mariupol, Alan Charlish in Medyka, Poland, Fedja Grulovic in Sighetu Marmatiei, Romania and Reuters bureaux Writing by Peter Graff Editing by Robert Birsel and Gareth Jones)