The Ukrainian government said on Saturday that Russia’s troops have shelled a mosque sheltering more than 80 people in the besieged city of Mariupol. There was no immediate word on casualties.

Bombardment intensified as Russian units fanned out to prepare their assault on the capital, Kyiv, a major political and strategic prize for Russian President Vladimir Putin. Ukrainians armed with portable missiles and Molotov cocktails have vowed to annihilate any Russian forces who enter the capital.

Now in its third week, the war has expanded to areas closer to NATO members Poland and Romania, with Ukrainian authorities saying Russian airstrikes attacked sites in two western cities. Meanwhile residents in some besieged areas have faced so much firepower they can’t even bury the dead.

Ukrainian President Volodymyr Zelenskyy has accused Russia of kidnapping the mayor of another, occupied city of Melitopol, calling it “a new stage of terror.”

The West has ramped up economic pressure on Russia, as the U.S. and its allies downgraded Russian’s trade status — the latest in efforts to further isolate Moscow for the invasion.

The war has forced more than 2.5 million people to flee Ukraine, while others seek refuge in basements, subway stations and underground shelters. The Ukrainian chief prosecutor’s office says at least 79 children have been killed since the start of the invasion.

Here are some key things to know about the war:

What’s Happening in Besieged Mariupol?

The Ukrainian Embassy in Turkey said Saturday that 86 Turkish nationals, including 34 children, were among the people who had sought safety in the mosque that was shelled. Ukrainian authorities have warned of a humanitarian catastrophe in Mariupol, besieged by Russian forces and where Ukraine’s military said Russian forces have captured the city’s eastern outskirts.

Repeated attempts to bring in food and evacuate civilians have been cancelled due to relentless Russian fire, while Moscow accuses the Ukrainians of violating cease-fires. Mariupol’s mayor says the 12-day assault has killed over 1,500 people.

Doctors Without Borders said some residents are dying for lack of medication, with the city without drinking water or medicine for over a week now. The aid group says people are resorting to boiling water from the ground or extracted from heating pipes.

What of the Missing Mayor of Occupied Melitopol?

Zelenskyy said the mayor of Melitopol, west of Mariupol and near Crimea, was kidnapped, and videos have emerged of local citizens there protesting the Russians’ presence, carrying flags and shouting.

Kirill Timoshenko, the deputy head of Ukraine’s presidential office, posted a video which he said shows armed men taking Mayor Ivan Fedorov across a square. Russian forces captured Melitopol, with a population of 150,000, on Feb. 26. Another video subsequently published online showed hundreds of Melitopol residents marching in a central square, demanding the mayor’s release. The video could not be immediately independently confirmed.

The prosecutor’s office of the Luhansk People’s Republic, a Moscow-backed rebel region in eastern Ukraine, accused Fedorov on its website of “terrorist activities.”

What’s Happening around the Capital and Elsewhere?

In the northeast, Russian forces were blockading Kharkiv, Ukraine’s second-largest city, even as efforts have been made to create new humanitarian corridors around it and other urban centers.

Ukraine’s emergency services reported that the bodies of five people were pulled from an apartment building that was struck by shelling in Kharkiv, including two women, a man and two children.

In Kyiv, an ammunition depot outside the city was shelled overnight, sending billowing black smoke into the sky, according to video provided by emergency workers. It was unclear immediately if were injuries or deaths.

The Russians’ push on Kyiv from the northeast appeared to be advancing, a U.S. defense official said, speaking on condition of anonymity to give the U.S. assessment of the fight. Combat units were moved up from the rear as the forces advanced to within 30 kilometers (19 miles) of Kyiv.

New commercial satellite images appeared to capture artillery firing on residential areas that stood between the Russians and the Ukrainian capital. The images from Maxar Technologies showed muzzle flashes and smoke from big guns, as well as impact craters and burning homes in the town of Moschun, 33 kilometers (20.5 miles) from Kyiv, the company said.

The strikes in western Ukraine, in the cities of Ivano-Frankiivsk and Lutsk, were confirmed by Russia, which said it used long-range weapons to put military airfields in the two cities “out of action.” Lutsk Mayor Ihor Polishchuk said four servicemen were killed and another six were wounded.

What has the AP directly witnessed or confirmed?

An Associated Press journalist witnessed tanks firing on a 9-story apartment block in Mariupol and was among a group of medical workers who came under sniper fire on Friday. Conditions at a local hospital there were deteriorating, electricity was reserved for operating tables and the hallways were lined with people with nowhere else to go.

Anastasiya Erashova, wept and trembled as she held a sleeping child. Shelling had just killed her other child as well as her brother’s child. “No one was able to save them.”

The city of 430,000 has been without food, running water and electricity for 10 days.

In Baryshivka, a village east of Kyiv, people surveyed damage and boarded up windows after a Russian bombing reduced a restaurant and a cinema to hanging metal, dust, glass and other debris. Ivan Merzyk, a 62-year-old resident, said: “Putin created this mess, thinking he will be in charge here. Ukrainians are a free nation. We are not going away from here and we don’t want to see any Russian here.”

Are People Being Safely Evacuated from Ukraine?

Ukrainian authorities said there are plans for several evacuation and humanitarian aid delivery routes. The top priority remains freeing people from the city of Mariupol and getting aid to its desperate population.

Buses were being sent Friday to multiple Kyiv suburbs to bring people to the capital, where authorities say half of the metropolitan area’s population, or around 2 million, has already fled.

There were also efforts to create new humanitarian corridors around the cities of Kherson in the south, Chernihiv in the north and Kharkiv in the east. Russian forces were blockading Kharkiv and pushing their offensive in the south around three cities and towns, including the hometown of Ukraine’s president, Kryvyi Rih.

Warsaw’s mayor has appealed for international help as the city becomes overwhelmed by refugees, with more than a tenth of all those fleeing the war arriving in the Polish capital. It’s train stations have become crowded transit hubs, with many camping out on the floor.

Are More Sanctions Against Russia Happening?

U.S. President Joe Biden announced an agreement Friday with other nations to revoke Russia’s “most favored nation” trade status, which would allow for higher tariffs to be imposed on Russian imports.

The U.S. also banned imports of Russian seafood, alcohol and diamonds.

Western nations have been largely united in punishing Russia economically.

French President Emmanuel Macron said Friday the European Union will continue applying pressure to Moscow and consider all options for more sanctions if Putin intensifies bombing and lays siege to Kyiv.