WARSAW, Poland (NewsNation) — Four weeks into the war in Ukraine, more than 3.5 million people have fled the country — the largest exodus of refugees in Europe since World War II — as Russian forces continue to batter Kyiv, Lviv, Mariupol and other important cities.

More than 2 million of those refugees have poured into Ukraine’s western neighbor, Poland, causing a 5% increase in the country’s total population since the war began.

“It was a bad situation. We didn’t have water, we didn’t have electricity, we slept and we didn’t know what would happen tomorrow,” said Elena, a woman who fled Kyiv for the safety of Poland.

Elena, who chose to be identified only by her first name, spoke with NewsNation’s Robert Sherman at a refugee transit center near Warsaw that has been housing up to 10,000 refugees at once.

“They had to leave their houses, they had to leave their husbands and they had to escape from their country. I cannot understand,” said Tomas Szypula, who ran the expo hall in Warsaw that’s been converted into a refugee transit center.

The goal with the transit center is to give refugees a temporary place to stay, eat and pick up supplies before they find more permanent shelters in other parts of Europe. The center also has a fully-functioning medical facility run by Warsaw Medical University professor, Maciej Maślanka.

“About 700 or 800 patients per day need help. We have a good system like a real hospital. So, other hospitals won’t be overcrowded because we have everything we need,” Maślanka said.

Despite being displaced and unsure of when she may return to her home country, Elena says she’s grateful for the help she’s received in Poland.

“We are so grateful because there’s everything we need. We have food, we have medical care, everything is good here. Thank you to other countries for helping us,” she said.