Mariupol theater building
On Wednesday, March 16th, Russia's Tass news agency headlined "Azov battalion militants blow up Mariupol theater building — Defense Ministry", and reported:
Militants of the Azov nationalist battalion blew up the Mariupol theater building, which they rigged with explosives earlier, Russian Defense Ministry announced Wednesday.

The Defense Ministry debunked Kiev's accusations of an airstrike on the theater building, where civilians could have been held hostage.

"During daylight on March 16, Russian aviation carried out no missions involving strikes on ground targets within Mariupol limits. According to the verified information, militants of the Azov nationalist battalion carried out another bloody provocation by blowing up the rigged theater building," the Ministry of Defense said.
The next day, CNN bannered "Survivors emerge from rubble of Mariupol theater bombed by Russia" and reported:
People sheltering in a theater in the Ukrainian city of Mariupol are emerging from the building after it was bombed, the former head of the Donetsk region said Thursday.

Hundreds of people were thought to have taken shelter in the theater amid the ongoing Russian siege of Mariupol.
CNN had not asked Russia's Ministry of Defense to show them the evidence they had backing up the claim that "During daylight on March 16, Russian aviation carried out no missions involving strikes on ground targets within Mariupol limits." Apparently, CNN was interested ONLY in information that was being supplied by Ukraine's government. Of course, 'reporting' in that way is only propaganda — not journalism.

See the detailed and fully documented account of this matter, here, which persuades me that Tass got it right, and that CNN got it wrong. I have checked out all of its linked-to sources and found them to be not only extremely credible but some of them are thoroughly mainstream, such as Deutsche Welle (the German public broadcaster), Newsweek, The Nation, Stanford University, and Amnesty International.

One source in it that is not mainstream is a posting by the breakaway republics in Ukraine's far-eastern Donbass region, and it's an announcement, dated March 12th, that:
The second provocation Zelensky is preparing for pictures in Western media, after unsuccessful provocation with Maternity hospital, [is that] Ukrainian forces ... got Mariupol women, children and old people into the Drama Theater building in order to show the whole world that [after it will be blown up] the place was bombed by the Russian Federation.. ... Don't be silent! We need to make more people know about this [preparation]!
How could the pro-Russian side have known about this in advance? If Russia had had any reason for bombing that theater, then the Ukrainian government's account of the matter would be worth considering. But none of that is the case here. The breakaway republics had gotten advance warning from resident(s) in nearby Mariupol — maybe from relative(s)s of hostages being held in that theater.

That rounding-up of those Mariupol civilians did occur, and Mariupol is (and has always been) ruled by the government in Kiev — the government that The West has been and is arming; so, this slaughter of those civilians definitely was either carried out by the government there (Ukraine) OR ELSE by the invading Russian forces. The question is: whom to believe? However, if Russia's forces did it, then WHY would the pro-Russian breakaway republics have warned on March 12th that this would be happening there? And WHY would Russia have selected that specific building to blow up? It had no military value, and only civilians were inside it. They had been inside it ever since March 12th.

Indeed: WHY would only civilians have been there? Why would no Ukrainian government forces (which control the city) have been there? What military purpose would have been served by doing this except to fool yet more people in The West to send to the Ukrainian government yet MORE weapons so they can kill the invading Russian troops?

That city is controlled by Ukraine's Azov Battalion. Mariupol happens to be a city just outside the Donbass breakaway region from Ukraine in Ukraine's southeast, and its citizenry were publicly protesting against the February 2014 forced overthrow of Ukraine's democratically elected President Viktor Yanukovych, for whom Mariupol's residents had overwhelmingly voted in the latest Ukrainian Presidential election, which was in 2010. U.S. President Barack Obama's Administration had hired Ukraine's highly organized racist-fascist anti-Russian "Right Sector" and other far-right forces to prepare and lead the 2013 "Maidan" demonstrations against Yanukovych and subsequently to be appointed themselves to the top national-security positions in the new, U.S.-installed, post-coup Ukrainian government. Here is a video, on 9 May 2014, showing Mariupol residents protesting peacefully against the overthrow of their President, and being shot by the newly installed government's police:

The pro-coup-regime (i.e., pro-U.S.) national Ukrainian newspaper Kyiv Post headlined "Avakov says 21 dead in Mariupol after clashes between police and separatists" and reported violent actions by the opponents of this new government:
Kremlin-backed "terrorists" kidnapped Mariupol police chief Valeriy Androshchuk during today's firefight over the local police headquarters, said lawmaker Oleh Liashko on his Facebook page who is in the Donetsk Oblast city at the moment.

He "fought until the end" but "terrorists" took him from the "burning police station in a car that was cut off by a sports utility vehicle," wrote Liashko. "The fighters stabbed the jeep driver with a knife and placed Androshchuk inside the car trunk and drove off in an unknown direction."
Liashko was one of Ukraine's leading far-right politicians and a strong backer of the U.S.-installed government; so, Liashko called the protesters "terrorists"; and, soon thereafter, the Ukrainian government officially introduced what they called an "Anti Terrorist Operation" in order to kill as many resisting people as possible anywhere in the country. (To resist the coup-installed government was to be a 'terrorist'.) This was virtually the beginning of Ukraine's civil war. But, even earlier, on 2 May 2014, the new government's murderous character was displayed in Odessa (in south-central Ukraine), where Right Sector forces trapped an unknown number of protesters in the Trade Unions Building — and burned them alive in it. The most heart-rending compendium of videos of that was shown here. This horrific event immediately sparked the protests throughout Ukraine's southeast, which started on May 9th of 2014, which began the civil war.

So, it's not surprising that, in the current battles, between the invading Russian soldiers and the soldiers of today's Ukraine (the defenders of the U.S.-imposed Ukrainian regime), human shields are being used for protecting ('shielding') the latter (America's proxy-forces in Ukraine).

The news-reports on March 17th, about the bombing of 1,200 civilians inside the Mariupol theater, was making a different use of the local civilians — not as human shields, but instead as victims of a false-flag attack by the Azov Battalion, in order to blame Russia so as to be able to receive yet more weapons from The West.