Nearly 120,000 people have so far fled Ukraine into Poland and other neighbouring countries amid the Russian invasion, the UN refugee agency said.
The number is going up fast as Ukrainians grab their belongings and rush to escape from a deadly Russian onslaught on their nation, including an attempt to take the capital Kyiv.
Poland has declared its border open to fleeing Ukrainians, even for those without official documents.
On Saturday a government official also said the country had sent a hospital train to pick up those wounded in the war in Mostyska, western Ukraine, and take them to Warsaw for treatment.
The train departed from the border town of Przemysl and had five carriages adapted to transport the wounded and four stocked with humanitarian aid for Ukraine’s Lviv district.
Some Ukrainian men were reportedly heading back into Ukraine from Poland to take up arms against Russian forces.
“Almost 116,000 have crossed international borders as of right now. This may go up, it’s changing every minute,” said Shabia Mantoo, spokeswoman of the UN High Commissioner for Refugees. “It’s very fluid and changing by the hour.”
The agency expects up to four million Ukrainians could flee if the situation deteriorates further.
Those arriving were mostly women, children and the elderly after Ukrainian President Volodymyr Zelensky on Thursday banned men of military age from leaving the country.
Ms Mantoo said most were heading to neighbouring Poland, Moldova, Hungary, Romania and Slovakia, and even some into Belarus — from where some Russian forces entered Ukraine.
She did not immediately have details on numbers by country, but by far the largest numbers were arriving in Poland, where two million Ukrainians have already settled to work in recent years, driven away by Russia’s first incursions into Ukraine in 2014 and seeking opportunities in the booming economy of the European Union neighbour.
Poland’s government said on Saturday morning that more than 100,000 Ukrainians had crossed the border in the past 48 hours.
At the Medyka border crossing, a line of vehicles waiting to enter Poland stretched nine miles into Ukraine, according to people crossing the border, Polish broadcaster TVN24 reported.