In his late night address to Ukrainians on Saturday, Zelenskyy said that Russian aggression "was not intended to be limited to Ukraine alone” and the “entire European project is a target for Russia.”

“That is why it is not just the moral duty of all democracies, all the forces of Europe, to support Ukraine's desire for peace," he said. ”This is, in fact, a strategy of defense for every civilized state."

His address came as civilians continued to flee eastern parts of the country before an expected onslaught and firefighters searched for survivors in a northern town no longer occupied by Russian forces.

Several European leaders have made efforts to show solidarity with the battle-scarred nation. Zelenskyy thanked the leaders of Britain and Austria for their visits Saturday to Kyiv, Ukraine's capital, and pledges of further support.

He also thanked the European Commission president and Canada's prime minister for a global fundraising event that brought in more than 10 billion euros (USD 11 billion) for Ukrainians who have fled their homes.

Zelenskyy repeated his call for a complete embargo on Russian oil and gas, which he called the sources of Russia's “self-confidence and impunity.”

“Freedom does not have time to wait,” Zelenskyy said. "When tyranny begins its aggression against everything that keeps the peace in Europe, action must be taken immediately."

More than six weeks after the invasion began, Russia has pulled its troops from the northern part of the country, around Kyiv, and refocused on the Donbas region in the east.

Newly released Maxar satellite imagery collected on Friday showed an 8-mile (13-kilometer) convoy of military vehicles headed south to the Donbas region through the Ukrainian town of Velykyi Burluk.

Western military analysts said an arc of territory in eastern Ukraine was under Russian control, from Kharkiv — Ukraine's second-largest city — in the north to Kherson in the south.

But counterattacks are threatening Russian control of Kherson, according to the Western assessments, and Ukrainian forces are repelling Russian assaults elsewhere in the Donbas, a largely Russian-speaking and industrial region.

Civilians were evacuating eastern Ukraine following a missile strike Friday that killed at least 52 people and wounded more than 100 at a train station where thousands clamored to leave.

Ukrainian authorities have called on civilians to get out ahead of an imminent, stepped-up offensive by Russian forces in the east. With trains not running out of Kramatorsk on Saturday, panicked residents boarded buses or looked for other ways to leave, fearing the kind of unrelenting assaults and occupations by Russian invaders that brought food shortages, demolished buildings and death to other cities.

“It was terrifying. The horror, the horror,” one resident told British broadcaster Sky, recalling Friday's attack on the train station. “Heaven forbid, to live through this again. No, I don't want to.”

Ukraine's state railway company said residents of Kramatorsk and other parts of the Donbas could flee through other train stations. Deputy Prime Minister Iryna Vereshchuk said 10 evacuation corridors were planned for Saturday.

Zelenskyy called the train station attack the latest example of war crimes by Russian forces and said it should motivate the West to do more to help his country defend itself.

Russia denied responsibility and accused Ukraine's military of firing on the station to turn blame for civilian casualties on Moscow. A Russian Defense Ministry spokesman detailed the missile's trajectory and Ukrainian troop positions to bolster the argument.

Major Gen Igor Konashenkov alleged Ukraine's security services were preparing a “cynical staged” media operation in Irpin, another town near Kyiv, intended to attribute civilian casualties to Russian forces — falsely, he said — and to stage the slaying of a fake Russian intelligence team that intended to kill witnesses. The claims could not be independently verified.

Western experts and Ukrainian authorities insisted that Russia attacked the station. Remnants of the rocket had the words “For the children” in Russian painted on it. The phrasing seemed to suggest the missile was sent to avenge the loss or subjugation of children, although its exact meaning remained unclear.

Ukrainian authorities have worked to identify victims and document possible war crimes in the north. The mayor of Bucha, a town near Kyiv where graphic evidence of civilian slayings emerged after Russian forces withdrew, said search teams were still finding bodies of people shot at close range in yards, parks and city squares.

Workers unearthed 67 corpses Friday from a mass grave near a church, according to Ukraine's prosecutor general. Russia has falsely claimed that the scenes in Bucha were staged.

Ukrainian and Western officials have repeatedly accused Russian forces of committing atrocities. A total of 176 children have been killed, while 324 more have been wounded, the Prosecutor General's Office said Saturday.

In an interview with The Associated Press inside his heavily guarded presidential office complex, Zelenskyy said he is committed to negotiating a diplomatic end to the war even though Russia has “tortured” Ukraine. He also acknowledged that peace likely will not come quickly. Talks so far have not included Russian President Vladimir Putin or other top officials.

“We have to fight, but fight for life. You can't fight for dust when there is nothing and no people. That's why it is important to stop this war,” he said.

Ukrainian authorities have said they expect to find more mass killings once they reach the southern port city of Mariupol, which is also in the Donbas and has been subjected to a monthlong blockade and intense fighting. The city's location on the Sea of Azov is critical to establishing a land bridge from the Crimean Peninsula, which Russia seized from Ukraine eight years ago.

As journalists who had been largely absent from the city began to trickle back in, new images emerged of the devastation from an airstrike on a theater last month that reportedly killed hundreds of civilians seeking shelter.

Ukrainian officials have pleaded with Western powers almost daily to send more arms and further punish Moscow with sanctions, including the exclusion of Russian banks from the global financial system and a total EU embargo on Russian gas and oil.

During his visit Saturday, Austrian Chancellor Karl Nehammer said he expects more EU sanctions against Russia, but defended his country's opposition so far to cutting off deliveries of Russian gas.

A package of sanctions imposed this week “won't be the last one,” the chancellor said, acknowledging that “as long as people are dying, every sanction is still insufficient.” Austria is militarily neutral and not a member of NATO.

British Prime Minister Boris Johnson's visit came a day after the U.K. pledged an additional 100 million pounds (USD 130 million) in high-grade military equipment. Johnson also confirmed further economic support, guaranteeing an additional USD 500 million in World Bank lending to Ukraine, taking Britain's total loan guarantee to up to USD 1 billion.

In the interview with AP, Zelenskyy noted the increased support but expressed frustration when asked if weapons and equipment Ukraine has received from the West is sufficient to shift the war's outcome.

“Not yet,” he said, switching to English for emphasis. “Of course it's not enough.”