What to know about the war in Ukraine

Two million people — half of them children — have fled Ukraine since Russia’s invasion, according to key U.N. agencies and the International Organization for Migration.

The U.N. High Commissioner for Refugees and UNICEF confirmed the figures as more people headed for the borders. Poland has received more than 1.2 million Ukrainian refugees, the most of any nation.

Civilians in one eastern Ukrainian city were leaving on buses Tuesday amid a 12-hour-long cease-fire in that area after Russia and Ukraine agreed on establishing five safe corridors for people to escape the fighting.

Meanwhile, Russian aircraft continued to bomb cities in eastern and central Ukraine overnight. Shelling pounded suburbs of the capital, Kyiv.

As the war entered its 13th day, food, water, heat and medicine have grown increasingly scarce in multiple cities facing electricity outages.

Here’s a look at key things to know about the war:

WHAT HAS BEEN DIRECTLY WITNESSED OR CONFIRMED?

Videos Tuesday showed people boarding buses, and multiple buses marked with a red cross driving along a snowy road as the eastern city of Sumy was given a safe corridor for evacuation.

Ukrainian Deputy Prime Minister Iryna Vereshchuk said both sides agreed to a cease-fire from 9 a.m. to 9 p.m. for the evacuation of civilians from Sumy. Those leaving include foreign students from India and China, she said.

The safe corridors were agreed on by Ukrainian and Russian officials during their third round of direct talks Monday. More talks are expected.

A video from Sumy showed the aftermath of an airstrike overnight with rescuers getting wounded out of the debris. A woman trapped under the rubble survived, according to the Ukrainian Interior Ministry. The video shows rescuers using bare hands and flashlights going through the rubble in the night, as well as machines cutting through concrete slabs to reach the victims.

WHAT ARE THE TWO SIDES SAYING ABOUT THE EVACUATIONS?

The Russian Defense Ministry has said civilians will be allowed to also leave the cities of Mariupol and the capital, Kyiv, where people have built hundreds of checkpoints to protect the city of nearly 4 million people.

The governor of the Kyiv Region, which surrounds the capital, said Ukraine was making arrangements to get people out of Irpin, which has been cut off from electricity, water and heat for four days.

Officials in Moscow say most of the corridors for fleeing civilians, however, will lead to Russia either directly or via Belarus. Russia’s ambassador to the U.N. suggested that humanitarian paths could give people a choice in where they want to go.

Ukrainian President Volodymyr Zelenskyy called for the expansion of humanitarian corridors on Tuesday. In an earlier video, he urged his people to keep resisting Russia’s assault. Ukraine’s foreign minister says more than 20,000 people from 52 countries have volunteered to fight in Ukraine.

WHAT ELSE IS HAPPENING ON THE GROUND?

Russian aircraft bombed cities in eastern and central Ukraine overnight, Ukrainian officials said. Shelling pounded suburbs of Kyiv. Bombs also hit oil depots in two other towns.

Ukraine’s Defense Ministry said Russian military actions have killed 38 children and wounded more than 70 since the start of the invasion. Overall, at least 400 civilians have been killed, the ministry said Tuesday. It was not possible to verify the figures.

The mayor of Lviv said the city in far western Ukraine is struggling to feed and house the tens of thousands who have fled there from other parts of the country. More than 200,000 Ukrainians displaced from their homes are in Lviv, filling up sport halls, schools and other buildings.

In the southern port city of Mariupol, an estimated 200,000 people — nearly half its population — are hoping to flee as hospitals there face severe shortages of antibiotics and painkillers. An official with Ukraine’s presidential office says humanitarian aid is being sent to the city.

A Russian general was killed in the fighting in Ukraine’s second-largest city, according to the Ukrainian military intelligence agency. He is the second Russian general reportedly killed since the invasion began. The report said he had fought with Russian forces in Syria and Chechnya. It was not possible to confirm the death independently. Russia has not commented.

HOW MANY PEOPLE HAVE BEEN KILLED?

The death toll of the conflict has been difficult to measure. The U.N. human rights office said Monday that it had confirmed the deaths of 406 civilians and wounding of 801 others through the end of Sunday. However, it acknowledged the actual figures are likely considerably higher.

The World Health Organization said six health care workers have been killed and nearly a dozen wounded in attacks. It has confirmed 16 attacks on health care facilities in Ukraine since Russia’s invasion began.

Ukrainian refugees continue to pour into neighboring countries, including Poland, Romania and Moldova. Among them are an unknown number of people with U.S. citizenship, though some haven’t been able to flee Ukraine yet.

WHAT IS THE GLOBAL IMPACT?

Surging prices for oil and other vital commodities, such as wheat used in subsidized bread and noodles, are rattling global markets.

Worries are growing that Russia’s invasion of Ukraine will upend already tight supplies of oil. Russia is one of the world’s largest energy producers, with prices surging even further by the possibility the U.S. might bar crude imports from Russia.

China’s President Xi Jinping criticized once again the sanctions imposed on Russia as “harmful to all sides,” according to a Chinese readout of a video summit Tuesday with the leaders of France and Germany.

Bulgaria said Tuesday it will not support sanctions against Russia that are harmful to its own economy. The country, which is a European Union and NATO member state, is heavily dependent on Russian oil and gas.

A growing number of multinational businesses have cut Russia off from vital financial services in response to Western economic sanctions. The most recent big name brands to suspend services in Russia are Netflix, the popular streaming service, and Estee Lauder, the New York-based cosmetics giant.

In the Middle East, the war in Ukraine is magnifying divisions in the region following Moscow’s role in the war in Syria. Russia has support among militant factions in Lebanon, Iraq and Yemen where ally, Iran, has influence.

Despite countries sending weapons to Ukrainian forces fighting the Russians, Western countries have rejected Ukrainian calls to impose a no-fly zone over the country. There are concerns such a move would risk dramatically escalating the conflict.