The Office of the UN High Commissioner for Refugees says more than 870,000 Ukrainians have fled their country as of Tuesday, and some 450,000 of them have crossed the border into neighboring Poland.

A station in the Polish capital Warsaw was crowded with people carrying suitcases and other luggage. They took trains heading for other areas in Poland or to other countries.

The Polish government is allowing Ukrainian citizens to ride trains and buses for free.

Outside the station, volunteers handed out water, disposable diapers and donated clothing. At a bus terminal adjacent to the station, exhausted Ukrainians were served warm soup.

A 63-year-old woman who fled with her two grandchildren said her home town was destroyed and her son had joined a local defense group. She said words cannot describe how worried she is.

The European Union will convene a meeting of interior ministers on Thursday for talks on support measures for displaced Ukrainians.

The ministers are scheduled to discuss proposals such as permitting Ukrainian citizens to stay more than 90 days and allowing them to work and study.

European Commission President Ursula von der Leyen said, "All those fleeing Putin's bombs are welcome in Europe," referring to Russian President Vladimir Putin.

The EU says more than 650,000 Ukrainians have fled to EU member states as of Tuesday.