Ukrainian soldiers help a family with a baby carriage flee across the Irpin River near the capital, Kyiv. Scenes like this are now common, with a growing number of cities and towns in Ukraine under attack by Russian forces. Most bridges in the area have already been destroyed.

The town of Irpin, named after the eponymous river, is only a few kilometers west of Kyiv. Russian troops fired mortar shells at the town all day Saturday, prompting civilians to seek refuge under a battered bridge. Even locals who had not planned to leave changed their minds and joined the crowds of people fleeing.

Some civilians managed to leave Irpin via bus. Many people were forced to cross the river on foot using a makeshift bridge made of old wooden planks, helped by Ukrainian soldiers. The flight was highly risky because of the heavy shelling by Russian forces.

Many Ukrainians fleeing their homes have opted for trains, making their way to various stations including the one in Irpin. This photo, taken on March 4, shows evacuees at the Irpin station headed for Kyiv, hoping to find a way of the country from there.

People fleeing the fighting and shelling have no idea what their cities and homes will look like when, and if, they return. Many of the trains, like this one from Irpin to Kyiv, are overcrowded, meaning people can't take much luggage with them.

After this house was struck by a mortar shell, the former inhabitants tried to salvage some personal belongings from the burning house. The UN has estimated that more than 1.4 million people have already fled Ukraine. Some experts have said up to 10 million people could leave the country.

An apartment block in Irpin came close to caving in after it was shelled last week. Increasing attacks by the Russian military on apartment buildings and other civilian infrastructure is a major reason why observers have predicted that refugee numbers will rise sharply.

Just a few days ago, this was an ordinary, thriving supermarket. But it's now become a symbol of war-time shortages, with shelves emptying quickly. Ukrainian soldiers collected the supplies of leftover food and water to distribute to local residents.

Ukrainians who stayed behind to defend their country have been receiving some basic combat training. In a cinema in the western city of Lviv, civilians were handed weapons and given a brief introduction to handling them. For many, it's the first time that they've taken up arms.

This 11th-century Eastern Orthodox church was built to rival the Hagia Sophia, in present-day Istanbul. Its mosaics and frescoes are prized for their impressive condition. The church greatly influenced subsequent temples, and together with the nearby monastic complex known as Kyiv-Pechersk Lavra, or Kyiv Monastery of the Caves, it helped the area become a center of Orthodox faith and thought.

With its dramatic mixing of styles, including Byzantine, Gothic and Baroque influences, this former residence of the Eastern Orthodox metropolitan bishop expresses the diverse religious and cultural identity of the Austro-Hungarian empire. Built by Czech architect Josef Hlavka from 1864-1882, the giant complex also includes a chapel, seminary and a monastery.

Founded in the late Middle Ages, the western city of Lviv was an important center of administration, religion and commerce for centuries. The modern city still bears its medieval hallmarks, including places of worship for various religious communities. It also boasts many Baroque buildings. Its architecture shows how Eastern European influences mixed with ones from Italy and Germany.

The Struve Arc is a chain of survey triangulations spanning more than 2,820 kilometers and 10 countries. Its southernmost point is in the Ukrainian town of Staro-Nekrasovka, on the Black Sea, while its northernmost point is in Hammerfest, Norway (above, in 1895; no photo from Ukraine available). Built from 1816-55, the collaborative structure helped determine Earth's exact shape and size.

The ruins of Tauric Chersonese, a 5th-century BC city founded by the Dorian Greeks, are located outside of Sevastopol, in southwest Crimea, which was illegally annexed by Russia in 2014. The site includes public building complexes, residential neighborhoods and early Christian monuments, well-preserved vineyard parcels and related systems, as well as remnants of Stone and Bronze age structures.

This UNESCO World Heritage Site is actually a series of 16 "tserkvas," or churches, that are spread out over Poland and Ukraine in the mountainous Carpathian region. The wooden log structures were built between the 16th and 19th centuries by both Orthodox and Greek Catholic communities. They exemplify the timber-building tradition of Slavic countries, and their interiors are also quite renowned.

Also located in western Ukraine is the natural World Heritage Site of ancient and primeval beech forests. The site in its entirety includes 94 areas in 18 countries. This photo is of the Uholka-Shyroki Luh forest, which is part of the world's largest primeval beech forest. Beech started spreading after the last Ice Age, 11,000 years ago, and are now part of pristine, complex ecological systems.

Kyiv residents have been improvising with various means to repel Russian forces. Here, members of the civil defense prepare Molotov cocktails.

Residents in Kyiv have formed civil defense units to protect their city and their families. Here an armed civil defense guard patrols a street in Kyiv after the curfew.

Those that are unable to flee the assault on Kyiv take shelter wherever they can find refuge. Many go to underground shelters or subway stations when the air-raid sirens go off.

Despite Russian assurances not to target civilian buildings, rockets and mortars have landed in residential areas like this apartment building in Kyiv, which was damaged on February 26.

A woman stands outside her badly damaged home after a rocket attack in Kyiv on Friday, February 25. Russian forces have hit civilian targets in several cities across Ukraine since Thursday.

During the night from Friday into Saturday morning, Russian attacks on Kyiv continued. This high-rise residential building in the capital was struck by a missile, according to Kyiv Mayor Vitali Klitschko. He urged city residents to stay out of harm's way.

People shelter in a basement as sirens warn of fresh attacks on Kyiv. Russia launched an all-out attack on Ukraine in the early hours of February 24.

Residents of Kyiv have also been taking to metro stations to stay safe as fighting rages on. The city has a population of roughly 3 million people.

Civilians evacuated by train from eastern Ukraine arrive at Lviv, in the country's west. Neighboring Poland, Hungary, and Romania are receiving scores of refugees.

Ukrainians carrying their belongings at Astely-Beregsurany border crossing, escaping to Hungary. Long queues have formed at the border, as people are desperate to leave.

Two Ukrainian refugees embrace as they arrive in Hungary after passing Beregsurany border crossing on February 26. Hungarian Prime Minister Viktor Orban vowed to provide humanitarian assistance for the new arrivals.

Volunteers prepare sandwiches for Ukrainian refugees fleeing to Romania via Siret border crossing, on Friday, February 25. Romanian authorities have readied for an influx of Ukrainians.

Ukraine's president, Volodymyr Zelenskyy, continues to send out defiant messages to his fellow Ukrainians boosting the morale of Ukrainian fighters as Russian troops were closing in on the city and huge explosions were heard early on February 27.

Volodymyr Zelenskiy was a well-known figure in Ukraine before he stood for president — but not as a politician. The comedian and actor starred in a 2015 TV show called "Servant of the People," in which he played a fictional president of Ukraine. In 2018 his production company formed a political party of the same name, and in December 2018 he announced he really was running for president.

Beating the odds, Zelenskiy was elected as president on April 21, 2019. The media-savvy TV star used social media to run an almost entirely online campaign and performed well in the polls from the start. The 41-year-old was also credited with appealing to a younger generation.

Zelenskiy was drawn into an international controversy early in his term. A July phone call with US President Donald Trump put Ukraine in the center of the Trump impeachment case. Trump is accused of withholding $400 million (€360 million) in aid to Ukraine to pressure Zelenskiy to investigate Trump's rival Joe Biden. Trump has denied wrongdoing and later tweeted it was a "PERFECT PHONE CALL."

Zelenskiy has made easing tensions with Russia a primary goal of his presidency. As a war between Ukrainian troops and pro-Russian separatists dragged on into its fifth year, Germany and France arranged a Paris summit between Russian President Vladimir Putin and Zelenskiy in December 2019. Among other things, the two sides agreed to several major prisoner exchanges.

Ukraine entered the headlines again in January 2020 after a Ukrainian airliner was shot down over Tehran, killing 176 people, on the same night that Iran fired missiles at US airbases in Iraq. Zelenskiy has been called on by the nations of the victims to act as a mediator with Iran to gain compensation for those affected. "The perpetrators must be held accountable," he said.

In January 2020, Ukrainian Prime Minister Oleksiy Honcharuk offered his resignation after audio tapes emerged in which he appeared to criticize Zelenskiy's knowledge of economics, saying the president needed to be better educated. Honcharuk resigned on Friday, but Zelenskiy said he would give his government a "second chance" — though he admitted the remarks were "unpleasant."