Russia claims its assault on Ukraine is aimed only at military targets, but civilians have been killed and injured during Europe's largest ground war since World War II.
A missile struck a high-rise apartment building in the city's southwestern outskirts near one of Kyiv's two passenger airports, Mayor Vitali Klitchsko said, leaving a jagged hole of ravaged apartments over several floors. A rescue worker said six civilians were injured.
The conflict has already driven hundreds of thousands of Ukrainians from their homes. U.N. officials said more than 120,000 Ukrainians have left the country for Poland, Moldova and other neighboring nations.
Saturday's street clashes followed two days of massive air and missile strikes as Russian soldiers moved in from the north, east and south. The assault pummeled bridges, schools and residential neighborhoods, and resulted in hundreds of casualties.
It was unclear in the fog of war how much of Ukraine was still under Ukrainian control and how much Russian forces have seized. Russia's defense ministry claimed the Russian military had taken full control of the southern city of Melitopol, about 22 miles (35 kilometer)s inland from the Azov Sea coast, and said Russia-backed separatists had made significant gains in the eastern region of Donbas.
Ukrainian and Western officials, however, say Ukrainian forces have managed to slow the Russian advance. Ukraine's Infrastructure Ministry said a Russian missile was shot down before dawn Saturday as it headed for the dam of the sprawling water reservoir that serves Kyiv.
Western officials believe Russian President Vladimir Putin is determined to overthrow Ukraine's government and replace it with a regime of his own. The invasion represented Putin's boldest effort yet to redraw the map of Europe and revive Moscow's Cold War-era influence. It triggered new international efforts to end the invasion, including direct sanctions on Putin.
Zelenskyy offered renewed assurance Saturday that the country's military would stand up to the Russian invasion. In a defiant video recorded on a downtown Kyiv street, he said he remained in the city and that claims the Ukrainian military would put down arms were false.
``We aren't going to lay down weapons. We will protect the country,'' the Ukrainian president said. ``Our weapon is our truth, and our truth is that it's our land, our country, our children. And we will defend all of that.''
Zelenskyy said in a second video later Saturday Moscow's plan to quickly seize the capital and install a puppet government had been unsuccessful. In an emotional speech, he accused the Russian forces of hitting civilian areas and infrastructure.
The president's whereabouts were kept secret after he told European leaders in a call Thursday that he was Russia's No. 1 target _ and that they might not see him again alive.
The U.S. government urged Zelenskyy early Saturday to evacuate Kyiv but he turned down the offer, according to a senior American intelligence official with direct knowledge of the conversation. The official quoted the president as saying that ``the fight is here`` and that he needed anti-tank ammunition but ``not a ride.''
The official spoke on condition of anonymity because he was not authorized to speak to the media.
Ukraine's health minister reported Saturday that 198 people,, including three children, have been killed and more than 1,000 others have been wounded since the Russian offensive started before dawn Thursday. It was unclear whether the figure included both military and civilian casualties.
Ukrainian officials say hundreds of Russians have been killed in the first days of fighting. Russian authorities released no casualty figures.
The U.N. estimates that up to 4 million could flee if the fighting escalates. Refugees arriving in the Hungarian border town of Zahony said men of fighting age were not being allowed to leave Ukraine.
``My son was not allowed to come. My heart is so sore, I'm shaking, I can't calm down, they did not let him come,'' said Vilma Sugar, 68.
City officials in Kyiv urged residents to seek shelter, to stay away from windows and to take precautions to avoid flying debris or bullets. Many spent the night in basements, underground parking garages and subway stations.
``We're all scared and worried. We don't know what to do then, what's going to happen in a few days,'' said Lucy Vashaka, 20, a worker at a small Kyiv hotel.
A British official, Armed Forces Minister James Heappey, said fighting in the capital was so far confined to ``very isolated pockets of Russian special forces and paratroopers'' and that ``the main armored columns approaching Kyiv are still some way off.''
The United States and other global powers moved to freeze the assets of Putin and his foreign minister Friday as part of tougher sanctions on Russia as the invasion reverberated through the world's economy and energy supplies.
Sports leagues also sought to punish Russia, and the popular Eurovision song contest banned Russian acts from the event's May finals in Italy.
Russia remained unbowed, vetoing a U.N. Security Council resolution demanding that it stop attacking Ukraine and withdraw troops immediately. The 11-1 vote, with China, India and the United Arab Emirates abstaining, showed significant opposition to Russia's invasion of its smaller, militarily weaker neighbor.
A senior Russian official on Saturday shrugged off the wide-ranging sanctions that the U.S., the European Union and other allies slapped on Russia as a reflection of Western ``political impotence.''
Dmitry Medvedev, the deputy head of Russia's Security Council, warned that Moscow could react to the sanctions by opting out of the last remaining nuclear arms pact, freezing Western assets and citting diplomatic ties with nations in the West.
``There is no particular need in maintaining diplomatic relations,'' Medvedev said. ``We may look at each other in binoculars and gunsights.''
NATO, meanwhile, decided Friday to send parts of the alliance's response force to help protect member nations in the east for the first time. NATO did not say how many troops would be deployed but added that it would involve land, sea and air power.
Late Friday, U.S. President Joe Biden signed a memo authorizing up to $350 million in additional security assistance to Ukraine, bringing the total security aid approved for Ukraine to $1 billion over the past year. It was not clear how quickly the aid would flow.
The assault was anticipated for weeks by the U.S. and Western allies and denied to be in the works just as long by Putin. He argued that the West left him with no other choice by refusing to negotiate Russia's security demands.
Putin has not disclosed his ultimate plans for Ukraine. Foreign Minister Sergey Lavrov gave a hint, saying, ``We want to allow the Ukrainian people to determine its own fate.'' Putin spokesman Dmitry Peskov said Russia recognizes Zelenskyy as the president, but would not say how long the Russian military operation could last.
Zelenskyy offered Friday to negotiate on a key Putin demand: that Ukraine declare itself neutral and abandon its ambition of joining NATO. The Kremlin said it accepted Kyiv's offer to hold talks, but it appeared to be an effort to squeeze concessions out of the embattled Zelenskyy instead of a gesture toward a diplomatic solution.