A total of 198 people have been killed and over 1,000 injured since the Russian offensive started before dawn on Thursday with massive air and missile strikes and troops forging into Ukraine from the north, east and south.

“Unfortunately, according to operative data, at the hands of the invaders we have 198 dead, including 3 children, 1,115 wounded, including 33 children,” Ukraine Health Minister Viktor Liashko wrote on Facebook. His statement did not make clear whether the total figure included both military and civilians.

The rise in the death toll came as Russian troops stormed towards Ukraine’s capital on Saturday, and street fighting broke out as city officials urged residents to take shelter. The country’s president refused an American offer to evacuate, insisting that he would stay. “The fight is here,” he said.

As dawn broke in Kyiv, it was not immediately clear how far the soldiers had advanced. Ukrainian officials reported some success in fending off assaults, but fighting persisted near the capital. Skirmishes reported on the edge of the city suggested that small Russian units were probing Ukrainian defences to clear a path for the main forces.

The street clashes followed fighting that pummelled bridges, schools and apartment buildings, and resulted in hundreds of casualties. By Saturday morning, when the small Russian units tried to infiltrate Kyiv, Ukrainian forces controlled the situation, said Mykhailo Podolyak, adviser to the Ukrainian presidential office.

Kyiv's mayor extended a 10 pm to 7am curfew he imposed two days ago to run from 5pm until 8am as of Saturday.

All civilians on the street during the curfew would be considered members of the enemy's sabotage and reconnaissance groups, Mayor Vitali Klitchsko said.

The swift movement of the Russian troops after less than three days of fighting further imperilled a country clinging to independence in the face of an invasion, which threatened to topple the democratic government.

Ukraine President Volodymyr Zelenskyy offered renewed assurance on Saturday that the country’s military would stand up to the Russian invasion. In a video recorded on a downtown street, he said he had not left the city and that claims that the Ukrainian military would put down arms were false.

“We aren’t going to lay down weapons. We will protect the country,” he 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 on Saturday that 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.

US 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 was urged to evacuate Kyiv at the behest of the US government but 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”.

City officials in Kyiv urged residents to take shelter, to stay away from windows and to take precautions to avoid flying debris or bullets.

The Kremlin accepted Kyiv’s offer to hold talks, but the Russian military continued its advance, laying claim on Friday to the southern Ukraine city of Melitopol. Still, it was unclear in the fog of war how much of Ukraine is still under Ukrainian control and how much or little Russian forces have seized.

As fighting persisted, Ukraine’s military reported shooting down an II-76 Russian transport plane carrying paratroopers near Vasylkiv, a city 40 kilometres south of Kyiv, an account confirmed by a senior American intelligence official. It was unclear how many were on board. Transport planes can carry up to 125 paratroopers.

A second Russian military transport plane was shot down near Bila Tserkva, 85km south of Kyiv, according to two American officials with direct knowledge of conditions on the ground in Ukraine.

The Russian military has not commented on either plane.

Wide-ranging sanctions

The US and other global powers slapped ever-tougher sanctions on Russia as the invasion reverberated through the world’s economy and energy supplies, threatening to further hit ordinary households. Sports leagues moved to punish Russia and even the popular Eurovision song contest banned it from the May finals in Italy.

Through it all, Russia remained unbowed, vetoing a UN Security Council resolution demanding that it stop attacking Ukraine and withdraw troops immediately. The veto was expected, but the US and its supporters argued that the effort would highlight Moscow’s international isolation. The 11-1 vote, with China, India and the United Arab Emirates abstaining, showed significant but not total opposition to Russia’s invasion of its smaller, militarily weaker neighbour.

Nato, meanwhile, decided to send parts of the alliance’s response force to help protect its 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.

Day Two of Russia’s invasion, the largest ground war in Europe since World War II, focused on the Ukrainian capital, where Associated Press reporters heard explosions starting before dawn. Gunfire was reported in several areas.

A large boom was heard in the evening near Maidan Nezalezhnosti, the square in central Kyiv that was the heart of protests which led to the 2014 ouster of a Kremlin-friendly president. The cause was not immediately known.

Five explosions struck near a major power plant on Kyiv’s eastern outskirts, said Klitschko. There was no information on what caused them, and no electrical outages were immediately reported.

UN officials reported 25 civilian deaths, mostly from shelling and airstrikes, and said that 100,000 people were believed to have left their homes. They estimate that up to four million could flee if the fighting escalates.

Zelenskyy tweeted that he and US President Joe Biden spoke by phone and discussed “strengthening sanctions, concrete defence assistance and an antiwar coalition”.

Late on Friday, Biden signed a memo authorising up to $350m in additional security assistance to Ukraine, bringing the total security assistance approved for Ukraine to $1 billion over the past year. It was not immediately clear how quickly the aid would flow.

Zelenskyy’s whereabouts were kept secret after Zelenskyy told European leaders in a call on Thursday that he was Russia’s No. 1 target — and that they might not see him again alive. His office later released a video of him standing with senior aides outside the presidential office and saying that he and other government officials would stay in the capital.

Zelenskyy earlier offered to negotiate on a key Putin demand: that Ukraine declare itself neutral and abandon its ambition of joining Nato. The Kremlin said Kyiv initially agreed to have talks in Minsk, then said it would prefer Warsaw and later halted communications. Russian Foreign Ministry spokeswoman Maria Zakharova said later that Kyiv would discuss prospects for talks on Saturday.

The assault was anticipated for weeks by the US and Western allies and denied to be in the works just as long by Putin. He argued the West left him with no other choice by refusing to negotiate Russia’s security demands.

In a window into how Putin views Ukraine and its leadership, he urged Ukraine’s military to surrender, saying: “We would find it easier to agree with you than with that gang of drug addicts and neo-Nazis who have holed up in Kyiv and have taken the entire Ukrainian people hostage.”

Playing on Russian nostalgia for World War II heroism, the Kremlin equates members of Ukrainian right-wing groups with neo-Nazis. Zelenskyy, who is Jewish, angrily dismisses those claims.

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 recognises Zelenskyy as the president, but would not say how long the Russian military operation could last.

Ukrainians abruptly adjusted to life under fire, after Russian forces invaded the country from three sides as they massed an estimated 150,000 troops nearby.

Residents of a Kyiv apartment building woke to screaming, smoke and flying dust. What the mayor identified as Russian shelling tore off part of the building and ignited a fire.

“What are you doing? What is this?” resident Yurii Zhyhanov asked Russian forces. Like countless other Ukrainians, he grabbed what belongings he could, took his mother, and fled, car alarms wailing behind him.

Elsewhere in Kyiv, the body of a dead soldier lay near an underpass. Fragments of a downed aircraft smoked amid the brick homes of a residential area. Black plastic was draped over body parts found beside them. People climbed out of bomb shelters, basements and subways to face another day of upheaval.

Read more: Dead bodies, crushed vehicles: Scenes from outskirts of Kyiv

“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.

At the Pentagon, press secretary John Kirby said the US believes the offensive, including its advance on Kyiv, has gone more slowly than Moscow had planned, noting that Ukraine forces have been fighting back. But he also said the military campaign is in an early stage and circumstances can change rapidly.

The Biden administration said on Friday that it would move to freeze the assets of Putin and Lavrov, following the European Union and Britain in directly sanctioning top Russian leadership.

Zakharova, the Russian Foreign Ministry spokeswoman, called the sanctions against Putin and Lavrov “an example and a demonstration of a total helplessness” of the West.

'This war will last,' says Macron

Meanwhile, French President Emmanuel Macron warned on Saturday that the world must brace for a long war between Russia and Ukraine.

“If [I] can tell you one thing this morning it is that this war will last,” Macron's told France's annual agriculture fair.

“This crisis will last, this war will last and all the crises that come with it will have lasting consequences,” Macron added, warning: “We must be prepared.”

Macron cut short his visit to the agriculture fair, usually one of the main fixtures on the French political calendar, in order to return to dealing with the crisis triggered by the Russian invasion.

“War has returned to Europe, this was chosen unilaterally by President [Vladimir] Putin, with a tragic humanitarian situation, a [Ukrainian] people who are resisting and a Europe that is there and resisting by the side of the Ukrainian people,” said Macron.

Additional input from AFP.