The UN refugee agency said Monday that more than 500,000 people have fled Ukraine since Russia invaded the country last week.

UN High Commissioner for Refugees Filippo Grandi gave the estimate in a tweet.

The latest and still growing count had 281,000 people entering Poland, more than 84,500 in Hungary, about 36,400 in Moldova, over 32,500 in Romania and about 30,000 in Slovakia, UNHCR spokeswoman Shabia Mantoo said.

The rest were scattered in unidentified other countries, she said.

Another train carrying hundreds of refugees from Ukraine arrived early Monday in the town of Przemysl in southeastern Poland.

In winter coats to protect them against near-freezing temperatures, with small suitcases, they lined up at the platform to the exit. Some waved at the cameras to show they felt relief to be out of the war zone. Many were making phone calls.

Meanwhile, U.N. human rights chief Michelle Bachelet says her office has confirmed that 102 civilians, including 7 children, have been killed, and 304 others injured in violence in Ukraine since Thursday, as she cautioned that the tally was likely a vast undercount.

Most of these civilians were killed by explosive weapons with a wide impact area, including shelling from heavy artillery and multi-launch rocket systems, and air strikes, Bachelet told the Human Rights Council in Geneva on Monday. The real figures are, I fear, considerably higher.

The count by the office of the U.N. High Commissioner for Human Rights follows strict methodology and verification measures.

Bachelet said millions of people have been forced to huddle in different forms of bomb shelters."

U.N. Secretary General Antonio Guterres told the council: The escalation of military operations by the Russian Federation in Ukraine is leading to escalating human rights violations.