Missiles pounded the Ukrainian capital on Friday as Russian forces pressed their advance and Ukrainian President Volodymyr Zelenskiy pleaded with the international community to do more, saying sanctions announced so far were not enough.

Air raid sirens wailed over the city of 3 million people, where some were sheltering in underground metro stations, a day after Russian President Vladimir Putin launched an invasion that has shocked the world. A Ukrainian official said a Russian plane had been shot down and crashed into a building.

A senior Ukrainian official said Russian forces would enter areas just outside the capital, Kyiv, later on Friday and that Ukrainian troops were defending positions on four fronts despite being outnumbered.

An estimated 100,000 people fled as explosions and gunfire rocked major cities.

Dozens have been reported killed. Russian troops seized the Chernobyl former nuclear power plant north of Kyiv as they advanced on the city from Belarus.

US and Ukrainian officials say Russia aims to capture Kyiv and topple the government, which Putin regards as a puppet of the United States.

Zelenskiy said he understood Russian troops were coming for him but vowed to stay in Kyiv.

“(The) enemy has marked me down as the number one target,” Zelenskiy said in a video message. “My family is the number two target. They want to destroy Ukraine politically by destroying the head of state.”

“I will stay in the capital. My family is also in Ukraine.”

Russia launched its invasion by land, air and sea on Thursday following a declaration of war by Putin, in the biggest attack on a European state since World War Two.

Putin says Russia is carrying out “a special military operation” to stop the Ukrainian government from committing “genocide” – an accusation the West calls a baseless fabrication.

He says Ukraine is an illegitimate state whose lands historically belong to Russia, a view which Ukrainians see as an attempt to erase their more than thousand year history.

Parts of the southern Kherson region and Hostomel airfield, northwest of the capital of Kyiv, were also reported to have been captured by the Russian forces.

Meanwhile, US President Joe Biden speaking at a press conference on Thursday ordered harsh new sanctions targeting Russia after it launched an all-out invasion of Ukraine, declaring that Russian leader Vladimir Putin “chose this war” and his country will bear the consequences.

The sanctions aim to impede Russia’s ability to do business in the world’s major currencies, namely dollars, euros, pounds and yen.

They also target Russian banks, oligarchs and high-tech sectors, Biden said. The United States and its allies will block assets of four large Russian lenders, impose export controls and sanction oligarchs.

Biden also said the U.S. will be deploying additional forces to Germany to bolster NATO after the invasion of Ukraine, which is not a member of the defense organization. Approximately 7,000 additional U.S. troops will be sent.

“Putin is the aggressor,” Biden said. “Putin chose this war, and now he and his country will bear the consequences.”