Ukrainian President Volodymyr Zelenskyy accused Russia on Saturday of kidnapping the mayor of a city, calling it “a new stage of terror.” Russian forces expanded their offensive in Ukraine, hitting new areas in the country's west.

The West 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 Russia 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.

Here are some key things to know about the war:

WHAT'S HAPPENING ON THE GROUND IN UKRAINE?

Zelenskyy said the mayor of the southern port city of Melitopol was kidnapped, equating it to the actions of “ISIS terrorists.”

“They have transitioned into a new stage of terror, in which they try to physically liquidate representatives of Ukraine’s lawful local authorities,” Zelenskyy said in a video address Friday evening.

Kirill Timoshenko, the deputy head of Ukraine’s presidential office, posted a video which he said shows armed men carrying Mayor Ivan Fedorov across a square. Russian forces captured Melitopol, with a population of 150,000, on Feb. 26.

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.”

The Biden administration, citing undisclosed American intelligence, had warned that Russia planned to detain and kill targeted people in Ukraine.

New areas in western Ukraine came under attack Friday, as Ukrainian authorities said Russian airstrikes hit in the western cities of Ivano-Frankiivsk and Lutsk — far from Russia’s main targets elsewhere in the country.

READ: Ukraine says shelling damaged cancer hospital

Russia 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.

New commercial satellite images appeared to show Russian artillery firing on residential areas that lie between Russian forces and the capital. The images from Maxar Technologies show muzzle flashes as well as impact craters and burning homes in the town of Moschun, outside Kyiv, the company said.

Ukrainian officials accused Russia of damaging a cancer hospital and several residential buildings in the southern city of Mykolaiv with heavy artillery.

The hospital’s chief doctor, Maksim Beznosenko, said several hundred patients were in the hospital when windows were blown out but that no one had been killed.

Russia’s Defense Ministry also said Friday that an offensive, led by fighters from the separatist-held Donetsk region, was further squeezing the southern port city of Mariupol. The Mariupol mayor’s office said Friday that the number of people killed during the 12-day siege has risen to 1,582.

Three more Russian airstrikes hit the industrial city of Dnipro in eastern Ukraine on Friday, killing at least one person, according to the Ukrainian interior ministry.

Thousands of civilians and soldiers on both sides are believed to have been killed in the invasion.

WHAT HAS THE AP DIRECTLY WITNESSED OR CONFIRMED?

More shelling and airstrikes pummeled Mariupol on Friday, leaving apartment complexes on fire as temperatures hovered around freezing. The city of 430,000 has been without food, running water and electricity for 10 days.

A newborn girl nestled against her mother after Russian airstrikes hit the Mariupol maternity hospital where the woman was to give birth. Mariana Vishegirskaya had her baby, Veronika, via cesarean section in another hospital on the city's outskirts a day after the Wednesday attack at hospital shocked the world.

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."

WHO ARE ‘VOLUNTEER’ FIGHTERS FOR RUSSIA AND UKRAINE?

Putin approved bringing “volunteer” fighters from Syria and other countries to join Russia’s offensive. Russia's defense minister said there had been “more than 16,000 applications” from the Middle East. He said many were from people who fought alongside Russia against the Islamic State group.

Kremlin spokesman Dmitry Peskov confirmed the recruits include fighters from Syria, where Russia intervened in the civil war in 2015 on the side of President Bashar Assad.

Meanwhile, the Ukrainian government says about 20,000 foreigners have joined the so-called International Legion for the Territorial Defense of Ukraine to fight the Russians.

The pro-Ukrainian fighters are given weapons when they arrive. About 100 Americans are among the fighters. The U.K. has warned veterans not to travel to Ukraine to fight there, saying those who do will be court-martialed.

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.

READ: China amplifies unsupported Russian claim of Ukraine biolabs

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.

WHAT ABOUT RUSSIA’S CLAIMS THAT BIOWEAPONS ARE BEING DEVELOPED IN UKRAINE?

Russia requested a meeting of the U.N. Security Council to discuss its baseless claims that the U.S. was conducting “biological activities” in Ukraine — an allegation that has been denied by both Washington and Kyiv.

At Friday's meeting, the United States accused Russia of “lying and spreading disinformation” as part of a potential false-flag operation — a scenario that U.S. Secretary of State Antony Blinken warned last month could happen as Putin seeks to justify his violent attack on Ukraine. U.S. Ambassador Linda Thomas-Greenfield said Friday that the U.S. believes Russia could use chemical or biological agents.

The Pentagon said Friday it supports labs in Ukraine that are devoted to identifying and responding to biological threats. The labs are owned and operated by Ukraine. The work of the labs is not secret, and experts say they are not being used for bioweapons.

China, meanwhile, is amplifying the unsubstantiated and inflammatory claims.

WHAT'S THE VIEW FROM INSIDE RUSSIA?

Moscow is making more moves to restrict access to foreign social media platforms. On Friday, Russian's communications and media regulator said it's blocking access to Instagram because it’s being used to call for violence against Russian soldiers.

That comes after Facebook owner, Meta Platforms, which also owns Instagram, said it had “made allowances for forms of political expression that would normally violate our rules on violent speech, such as ‘death to the Russian invaders’.” Meta's statement stressed it would not allow credible calls for violence against Russian civilians.

Russia has already blocked access to Facebook and limited access to Twitter, but Twitter has launched a privacy-protected version of its site to bypass surveillance and censorship.

Meanwhile, YouTube started blocking global access to channels associated with Russian state-funded media, and said it is removing content about Russia’s invasion of Ukraine that violates its policy about minimizing or trivializing "well-documented violent events.”

Meta has barred Russian state media from Instagram and Facebook.

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.