(CNN) The Prime Ministers of Poland, Slovenia and the Czech Republic reaffirmed their support for Ukraine amid the ongoing Russian invasion during a meeting Tuesday with Ukrainian President Volodymyr Zelensky and Prime Minister Denys Shmyhal in capital Kyiv.
Following the meeting, Polish Prime Minister Mateusz Morawiecki called for the European Union to "very quickly" grant Ukraine candidate status.
"We are here to admire your fight against such a cruel aggressor. This invasion has to stop," Morawiecki said. "Those who are killed by (Russian President Vladimir) Putin, they can never be forgotten. They are not forgotten."
He also emphasized Poland, which shares a 310-mile border with Ukraine, would try to help Ukraine organize its defenses.
"We will never leave you alone. We will be with you. Because we know you are fighting not only for your homes, for your freedom, for your security, but also for ours," he said.
Czech Prime Minister Petr Fiala said having an in-person discussion with Zelensky was "something really special."
"The main goal of our visit and the main message of our mission is to say to our Ukrainian friends that they are not alone, that Europe stands with you," Fiala said.
Fiala said he wanted to assure Ukrainians we are "hosting your wives and children" and providing them with "refuge" in the Czech Republic.
The Czech Republic has now taken in 250,000 refugees, according to the prime minister, who said they will "continue to provide more aid and support."
Zelensky thanked the EU leaders for their "wonderful support" when "so many other ambassadors have left Ukraine because of the full-scale Russian invasion."
"Most important, is that we truly trust these leaders," Zelensky said. "When we are talking about the security guarantees, about our future in the European Union, or when we talk about the sanctions policy, we are 100% assured that whatever we are discussing, whatever we talk about, this will reach a positive outcome for our country."
He continued that with "friends like this," Ukraine "can win."
Poland's Morawiecki, Slovenian Prime Minister Janez Janša and the Czech Republic's Fiala departed on a train before 9 a.m. local time, the head of the chancellery of the Prime Minister of Poland, Michal Dworczyk, said. The train departed from Poland, a press officer for the Czech government told CNN later on Tuesday.
The purpose of the visit is "to confirm the unequivocal support of the entire European Union for the sovereignty and independence of Ukraine and to present a broad package of support for the Ukrainian state and society," a government spokesperson said.
They said the trip to Kyiv had been organized in agreement with European Council President Charles Michel and European Commission President Ursula von der Leyen, and added that the international community would be informed about the delegation visit through international organizations, including the United Nations.
"At such breakthrough times for the world, it is our duty to be where history is forged; because it is not about us, but about the future of our children who deserve to live in a world free from tyranny," Morawiecki said in a Facebook post on Tuesday.
Morawiecki said he and the other leaders were going to Kyiv to "show Ukrainians our solidarity" and denounced "Putin's criminal aggression against Ukraine."
The EU leaders visit came hours after Kyiv came under attack from multiple directions on Tuesday. Four people were killed when a 16-story building in a residential area of western Kyiv was shelled, city mayor Vitali Klitschko said. At least four residential buildings were hit by air strikes on Tuesday morning.
Ahead of the meeting with Zelensky on Tuesday, Slovenia's Janša sent a message to Ukraine, posting on Twitter: "Thank you for not only defending your homeland and Europe as a territory, but for defending the very core of European values and our way of life. Your fight is our fight and together we will prevail."
More than 3 million people have fled Ukraine since the start of the Russian invasion on February 24, the International Organization for Migration said Tuesday.
Poland has been the biggest recipient of refugees from Ukraine, with more than 1.8 million people entering the country as of Tuesday, according to the United Nations High Commissioner for Refugees (UNHCR).
UNHCR chief Filippo Grandi has praised Morawiecki and his government for their "exceptional support" of Ukrainian refugees.
Poland also put forward a plan to send fighter jets to Ukraine, although this was rejected by the US.
Meanwhile, the Czech Republic has bolstered the military aid it is providing to Ukraine, with a supplementary aid package worth at least $31.5 million, in addition to the $8.5 million shipment it already sent in February.
Prime Minister Fiala said last month his country was sending "machine guns, submachine guns, sniper rifles and pistols and their corresponding ammunition valued at CZK 188 million," to support the Ukrainian government in its fight against Russia.