Nearly 45,000 more Ukrainian refugees fled in 24 hours, the United Nations said Monday, although many were trapped in their regions or were staying put hoping the war will end soon. The UN refugee agency UNHCR said 4,547,735 Ukrainians had fled the country since the Russian invasion on February 24 — a figure up 44,781 on Sunday’s update. It is Europe’s fastest-growing refugee crisis since World War II. Women and children account for 90 percent of those who have left the country, with men aged 18 to 60 eligible for military call-up and unable to leave. The UN’s International Organization for Migration estimates that 7.1 million people have fled their homes but are still in Ukraine. “We have people in areas where there is still military Russian aggression that does not allow them to move. But there are others who prefer to stay because they hope, as we all hope, that this war will come to an end as soon as possible,” IOM chief Antonio Vitorino told CNN. “We are very concerned not just with the safety of the people, but also to make sure that we assess their needs: cash, health, medicine, food, shelter and even clothes.” The IOM says that in addition to Ukrainian refugees, more than 210,000 non-Ukrainians living, studying or working in the country have also left. In total, more than a quarter of the population have been forced to flee their homes. Before the Russian invasion, Ukraine had a population of 37 million in the regions under government control, excluding Russia-annexed Crimea and the pro-Russian separatist regions in the east.