WARSAW, Poland—Nearly 120,000 people have so far fled Ukraine into Poland and other neighboring countries in the wake of Russian invasion, the U.N. refugee agency said on Saturday. Poland has declared its border open to fleeing Ukrainians, even for those without official documents. On Saturday a government official also said that the country sent a hospital train that will pick up those wounded in the war in Mostyska, in western Ukraine, and bring them to Warsaw for treatment. The hospital train departed the border town of Przemysl and has five carriages adapted to transport the wounded and four stocked with humanitarian aid for Ukraine’s Lviv district. “Almost 116,000 have crossed international borders as of right now. This may go up, it’s changing every minute,” said Shabia Mantoo, the spokeswoman of the U.N. High Commissioner for Refugees. “It’s very fluid and changing by the hour.” The agency expects up to 4 …