The United Nations Refugee Agency says the situation in Ukraine could lead to Europe's largest refugee crisis this century.
Since Russia invaded the country, the U.N. says approximately 660,000 people have left Ukraine.
"Most have fled to Poland, Hungary, Moldova, Romania, Slovakia, while others have moved towards various other European countries," the U.N. said in a statement. "We are also aware that a sizeable number has moved to the Russian Federation."
While many people fleeing Ukraine have been greeted with hospitality in other countries, they have also had to wait hours to cross the border.
The U.N. says some people who were trying to get into Poland had to wait up to 60 hours. In other countries, it's taken about a day to reach the border, the U.N. stated.
The U.N. Refugee Agency said it's working to help people who have not left Ukraine by delivering assistance and "strengthening nationwide hotlines to provide critical protection information to displaced civilians."