Russian forces surrounded the cities across Ukraine Sunday morning, blocking civilians from fleeing the violence and firing on civilian targets.

Russia continued its bombardment of various cities, launching airstrikes stepping up shelling outside of Kyiv's capital.

According to local reports, air raid alarms echoed again in nearly every region of Ukraine.

Russian aircraft dried eight missiles that hit the Yaroviv International Peacekeeping and Security Center near Lviv, just 10 miles from the Polish border, around 6 a.m. local time Sunday, Ukrainian officials said on Sunday.

The IPSC is a massive military base that includes a training center for soldiers, mainly for peacekeeping missions, supported by the United States in the past.

In the strategic port city of Mariupol in Ukraine's South- which incessant Russian bombings have devasted- efforts to deliver food, water, and medicine into the city of 430,000 people were prevented by another day of brutal shelling Saturday.

According to the mayor's office, more than 1,500 people have died in Mariupol during the siege, which said the shelling has even interrupted efforts to bury the dead in mass graves.

Talks between Ukrainian and Russia attempting to reach a cease-fire agreement fell apart on Saturday.

The U.S. has pledged to send an additional $200 million in weapons. Still, Russia issued a stern warning to the U.S. and its allies that transporting weapons to Ukraine will be considered "legitimate targets" for Russian forces.

French and German leaders spoke Saturday with Russian President Vladimir Putin in a failed attempt to reach a cease-fire, during which Putin laid out his conditions for ending the fighting: Ukraine must drop its bid to join NATO and adopt a neutral status; acknowledge Russian controlled regions of Luhansk and Donetsk, and to demilitarize.

Ukraine President Volodymyr Zelensky has accused Russia of starting "a new stage of terror" and compared Russian soldiers to "ISIS terrorists" after they abducted the mayor of Melitopol on Friday.

"Ukraine will stand this test. We need time and strength to break the war machine that has come to our land," Zelensky said during his nightly address on Saturday.

Moscow said it would establish humanitarian corridors to evacuate civilians out of conflict zones, but Ukrainian officials have accused Russia of disrupting those paths and firing civilians.

Ukraine's Deputy Prime Minister Iryna Vereshchuk said just nine of 14 agreed-upon corridors were open on Saturday and that about 13,000 people had used them to evacuate around the country.

Russian soldiers pillaged a humanitarian convoy trying to reach Mariupol and blocked another, a Ukrainian official said. Russian forces are now in control of the city's eastern outskirts as they escalate their siege on the port to establish a land corridor to Crimea, which it seized from Ukraine in 2014.

Mariupol has been without water or electricity for over a week. Aid group Doctors without borders said residents are dying from a lack of medication and are draining heating pipes for drinking water. In Irpin, a suburb about 12 miles northwest of central Kyiv, bodies layout in the open on streets and in a park on Saturday.

Zelensky tried to rally his people to keep up their resistance against Russian invaders. "We don not have the right to let up our defense, no matter how difficult it may be," he said.

On Saturday, Zelensky reported that 1,300 Ukrainian soldiers had died since the Russian invasion began 17 days ago on Feb 24. Ukraine's government says that thousands of civilians have been killed, including at least 79 Ukrainian children. At least 2.5 million people have fled the country. According to the United Nations refugee agency, over 1.5 million have crossed into Poland.

According to the World Health Organization, Russian forces have hot at least two dozen hospitals and medical facilities.

The Russian invaders appear to have struggled far more than expected against the fierce defense of embattled Ukrainian fighters; however, their outgunned and outnumbered the ceaseless Russian assaults could wear down forces.