experts warning that europe could be facing its largest refugee crisis this century. the u.n. saying tonight that 1 million people have already fled ukraine since russia invaded, most crossing in through neighboring poland and 100,000 seeking asylum in hungary. >> reporter: the train to safety arrives 20 minutes late, rolling across the border from ukraine, loaded with civilians, all fleeing the world's newest war zone. it is a carefully managed procession, families emerging one by one, expatriots from south asia and africa and of course ukrainians welcomed by hungarian officials and aid workers. each handed a solidarity ticket, a free seat on another train to