“We have to do this,” she said. “Ukrainians fight for us and they fight for European human values.”

Nearly 150,000 Ukrainians have fled to European neighbors, mainly Poland, Hungary, Moldova, Slovakia and Romania, since Russia invaded Ukraine on Thursday, the United Nations refugee agency said Saturday.

Thousands more are still trying to get through the clogged borders, waiting in the cold for hours on end in cars or on foot with just the bare minimal belongings.

What could become Europe’s biggest humanitarian crisis since 2015 — when more than 1 million refugees mainly from Syria, Iraq, and Afghanistan arrived and triggered a continentwide crisis — is swiftly unfolding.

So far, European leaders and communities say they are ready to welcome Ukrainian refugees — including countries such as Slovakia, Hungary and Poland, which have previously hardened their borders in the face of other waves of refugees.

In many cases, volunteers with locally funded food, clothes and warm rooms await those arriving. “I see that there is a huge response from regular citizens,” Lempart said. “We have calls [for donations] from all over Europe and the world.”

Meanwhile, the situation keeps getting more grave: The United Nations warned Friday that up to 5 million of Ukraine’s 44 million people could become refugees if Russia’s attacks Ukraine continue. It’s mainly women, children and the elderly fleeing — as males ages 18 to 60 are barred from leaving Ukraine after President Volodymyr Zelensky called on Ukrainians to take up arms and defend the country.

Poland, which has seen the biggest influx, pledged to set up reception centers along its 300-mile border to offer food, medical care and other resources. This month, thousands of soldiers from the U.S. Army’s 82nd Airborne Division deployed there to help with preparations.

“We will do everything to provide safe shelter in Poland for everyone who needs it,” Polish Interior Minister Mariusz Kaminski said Thursday.

Poland is already home to around 2 million Ukrainians, many of whom fled there after Russia’s 2014 takeover of Crimea and the start of the eight-year-long war in eastern Ukraine. The United Nations has estimated that another 1 million to 3 million Ukrainians could join them.

Other neighbors, such as Hungary and Slovakia, are sending troops to their borders to aid with the intake of refugees. In Romania, volunteers are similarly queuing to offer food and free accommodation. Ukrainians do not need a visa to enter these countries, as they can stay anywhere in the European Union’s Schengen Area for up to 90 days visa-free. (This agreement is set to change at the end of 2022).

Ireland, which is not part of the Schengen Area, said Thursday that it would waive its visa requirement for Ukrainians. The first minister of Wales, Mark Drakeford, said his “nation of sanctuary” was ready to welcome Ukrainians.

Other governments, including Britain’s, have pledged to help Ukraine but have not loosened or clarified their immigration policies.

Ukraine is not a member of the European Union — the main alliance of European countries that Russian President Vladimir Putin considers an existential threat.

But Ylva Johansson, the European commissioner for home affairs, told Euronews on Wednesday that the E.U. was “quite well prepared” to absorb Ukrainian refugees as a matter of “unity” and “solidarity.”

“We are looking into the support from the E.U. asylum agency with processing asylum applications, the support from Frontex with registration and border management, and the support from Europol as well,” she said.

The Ukraine crisis has pushed some countries to reform their policies. While Austria did not accept Ukrainian refugees during the 2014 Crimea crisis, Austrian Chancellor Karl Nehammer said Thursday that he would welcome them in this time as a part of Europe — the very idea that Putin rejects.

“We are a European family, and families stand by each other,” he said.

Slovakian officials said Saturday that the country will provide monthly stipends to Slovakians who support and house displaced Ukrainians. Back in 2015, however, the country declared it would not accept Syrian refugees — unless they were Christian.

But these kinds of disparities have frustrated refugee advocates, who have long criticized European leaders for pledging to support refugees while falling short on funding programs and maintaining often harsh, unwelcoming restrictions.

In recent years, European countries have aimed to stop — at times violently — the flow of largely non-White and non-Christian migrants and asylum seekers fleeing other conflicts and wars in the Middle East, Afghanistan and Africa.

In November, Poland forcibly denied entry to asylum seekers from the Middle East and Africa who became caught in a geopolitical standoff between Russia and Europe as they tried to enter from neighboring Belarus.

In 2015, Hungarian Prime Minister Viktor Orban built a fence to cut off one of the migrant routes. More recently, he supported a law making it a crime to help immigrants who entered Hungary illegally to apply for asylum.

Backlash to the influx of refugees in 2015 and 2016 emboldened the far-right in some European countries and led to a wave of anti-immigrant sentiment and policies.