KYIV, Ukraine — Kyiv residents braced Saturday for another night sheltering underground, as Russian troops closed in on Ukraine's capital and skirmishes were reported on the outskirts. Ukraine's leader, meanwhile, claimed the country's forces had repulsed the Russian assault, and he vowed to keep up the struggle and appealed for more help from the outside world.

"The real fighting for Kyiv is ongoing," President Volodymyr Zelenskyy said in a video message in which he accused Russia of hitting infrastructure and civilian targets.

"We will win," he said.

Central Kyiv appeared quiet on Saturday, though sporadic gunfire could be heard. And fighting on the city's outskirts suggested that small Russian units were trying to clear a path for the main forces. Britain's defense ministry said the bulk of Russian forces were 19 miles from the middle of the city.

Kyiv Mayor Vitali Klitschko extended a curfew he imposed Thursday to run from 5 p.m. until 8 a.m. He said "all civilians on the street during the curfew will be considered members of the enemy's sabotage and reconnaissance groups."

Russia claims its assault on Ukraine is aimed only at military targets, but bridges, schools and residential neighborhoods have been hit since the invasion began Thursday with air and missile strikes and Russian troops entering Ukraine from the north, east and south.

Ukraine's health minister reported Saturday that 198 people, including three children, have been killed and more than 1,000 others have been wounded during Europe's largest land war since World War II. It was unclear whether the figure included both military and civilian casualties.

In Kyiv, a missile struck a high-rise apartment building in the southwestern outskirts near one of Kyiv's two passenger airports, leaving a jagged hole of ravaged apartments over several floors. A rescue worker said six civilians were injured.

The conflict has driven thousands of Ukrainians from their homes in search of safety. U.N. officials said more than 120,000 Ukrainians have left the country for Poland, Moldova and other neighboring nations.

Russian President Vladimir Putin sent troops into Ukraine after he spent weeks denying that's what he intended, all the while building up a force of almost 200,000 troops along the countries' borders. He claims the West has failed to take seriously Russia's security concerns about NATO, the Western military alliance that Ukraine aspires to join. But he has also expressed scorn about Ukraine's right to exist as an independent state.

Putin has has not disclosed his ultimate plans for Ukraine or said how long the Russian military operation could last. Western officials believe Putin is determined to overthrow Ukraine's government and replace it with a regime of his own, redrawing the map of Europe and reviving Moscow's Cold War-era influence.

It was unclear in the fog of war how much territory Russian forces have seized. Western governments claimed stiff Ukrainian resistance had slowed the Russian advance, and Russia does not yet control Ukraine's skies.

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, and Ukraine said a Russian military convoy was destroyed near the city early Saturday. Footage showed soldiers inspecting burned-out vehicles after Ukraine's 101st brigade reported destroying a column of two light vehicles, two trucks and a tank. The claim could not be verified.

In addition to Kyiv, the Russian assault appeared to focus on Ukraine's coastline, stretching from the Black Sea port of Odesa, in the west near the border with Romania, to the Azov Sea port of Mariupol in the east.

If the Russian troops succeed, Ukraine will be cut off from access to all of its sea ports, which are vital for its economy. In Mariupol, Ukrainian soldiers guarded bridges and blocked people from the shoreline amid concerns the Russian navy could launch an assault from the sea.

Fighting also raged in two territories in eastern Ukraine that are controlled by pro-Russian separatists. Authorities in the city of Donetsk said hot water supplies to the city of about 900,000 were suspended because of damage to the system by Ukrainian shelling. It was unclear how long repairs to the system would take.

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. Zelenskyy issued a defiant video recorded on a downtown Kyiv street early Saturday, saying he remained in the city.

"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."

Hundreds of thousands of Ukrainians have been on the move, seeking safety in the west of the country or beyond. 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 between 18 and 60 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.

Hungary and Poland both opened their borders to Ukrainians with or without travel documents. At Poland's Medyka crossing, some said they had walked for 15 miles to reach the border.

"They didn't have food, no tea, they were standing in the middle of a field, on the road, kids were freezing," said Iryna Wiklenko as she waited on the Polish side for her grandchildren and her daughter-in-law to make it across.

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 Friday night in basements, underground parking garages and subway stations, and prepared to do the same again on Saturday.

"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.

The United States and other NATO allies have sent weapons and other aid to Ukraine and beefed up their troops on NATO's eastern flank, but ruled out deploying troops to fight Russia.

Instead, the U.S., the European Union and other countries have slapped wide-raging sanctions on Russia, freezing the assets of Russian businesses and individuals including Putin and his foreign minister.

French maritime officials seized a Russian-flagged cargo ship carrying cars for potential sanctions breaches and took it to a port for investigation.

Zelenskyy appealed for tougher sanctions, urging holdout countries in Europe to agreed to cut Russia out of the SWIFT international payments system.

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 sanctions 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 cutting 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."

Diplomatic efforts to end the bloodshed appeared to have faltered. Zelenskyy offered Friday to negotiate a key Russian 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.