Russian forces continued to shell Ukraine's strategic port city of Mariupol on Saturday despite agreeing to a temporary cease-fire to allow civilians to evacuate, according to the regional governor.

"Due to the fact that the Russians do not observe the regime of silence and continue shelling of Mariupol and its environs, for security reasons, the evacuation of the population has been postponed," Donetsk Oblast Gov. Pavlo Kyrylenko said in a statement posted on social media. "We ask people to leave the gathering places and go to the shelters. Additional information about the evacuation will be posted soon. Police officers will also use loudspeakers to inform the city's residents."

The Associated Press reported that Kyrylo Tymoshenko, deputy head of the Ukrainian president's office, confirmed that the evacuation effort in Mariupol was stopped because the city remained under fire on Saturday.

"The Russian side is not holding to the ceasefire and has continued firing on Mariupol itself and on its surrounding area," Tymoshenko said, according to AP. "Talks with the Russian Federation are ongoing regarding setting up a cease-fire and ensuring a safe humanitarian corridor."

Earlier Saturday, the Russian Ministry of Defense announced that it has agreed with Ukrainian forces to open humanitarian corridors in Mariupol, a strategic port in the southeast, and in the eastern city of Volnovakha between 10 a.m. and 5 p.m. Moscow time. The deal was reached during the second round of talks between Russian and Ukrainian delegations earlier this week.

Mariupol has been under ferocious, indiscriminate bombardment with heavy artillery and missile strikes for days, causing the city to sometimes lose power and water. Local officials have described bodies strewn across the streets because authorities are unable to collect them.

-ABC News' Patrick Reevell

Russia announced Saturday a temporary cease-fire in two besieged cities of Ukraine to allow civilians to evacuate.

The Russian Ministry of Defense said in a statement carried by state news agencies that it has agreed with Ukrainian forces to open humanitarian corridors in the strategic port of Mariupol and the eastern town of Volnovakha beginning at 10 a.m. Moscow time.

"Starting at 10 a.m. Moscow time today, on March 5, the Russian side declares a ceasefire and opens humanitarian passages for civilians to leave Mariupol and Volnovakha," the ministry said. "Humanitarian passages and exit routes have been coordinated with the Ukrainian side."

There was no immediate confirmation from Ukraine, and it was unclear how long the evacuation routes would remain open.

-ABC News' Anastasia Bagaeva

Deb Parry, who is currently leading Save the Children’s team in Poland, told ABC News she has never seen anything like the outpouring of help on the Polish border.

“I’ve worked for Save the Children for 30 years and I’ve never seen anything like it. There’s a phenomenal amount of aid being sent. Everything these families could possibly need.”

“They even sent skis!” she exclaimed.

The donations are piling up all over Poland and being dropped near the crossings and reception centers throughout the country. Piles of skis and snowboards were stacked up at Dolhobyczow, a village near the Ukraine border.

“I’m not sure why people think they need skis,” Parry said.

Because of this effort by local communities, Save the Children can focus on things other than the distribution of necessities. More than 700,000 refugees have streamed across the Poland border since Russia invaded Ukraine on Feb. 24 -- almost all of whom are women and children.

Save the Children is helping parents talk to their children about war. They have teamed up with the telecom companies providing SIM cards and hand out leaflets with information for how best to cope in these trying conditions.

“It’s important to keep children in some sort of a routine,” Parry explained, adding that parents or caretakers need to be careful about what they expose children to.

“Don’t have the news on all the time,” she said.

-ABC News' Zoe Magee and Chris Donato

Representatives from Facebook and Twitter provided updates about their services after the Russian government announced it would block both services.

Twitter security chief Yoel Roth said the company has not confirmed its services are completely disabled in Russia during a public panel Friday evening.

Meta, Facebook's parent company, put out a statement contending, "despite the Russian government’s announcement that they will be blocking Facebook, we are working to keep our services available to the greatest extent possible."

Meta added that "ads targeting people in Russia will be paused, and advertisers within Russia will no longer be able to create or run ads anywhere in the world, including within Russia."

-ABC News' Quinn Owen

The Russian forces charging toward Kyiv haven't made progress in the last day as they face Ukrainian resistance and low food and gas supply, a senior U.S. defense official told reporters Tuesday.

However, it could be a deliberate pause, the official said. "Part of the stall could be ... as a result of their own self-determined sort of pause in operations -- that they are possibly regrouping, rethinking, reevaluating," the official said.

The U.S. believes Russian forces "have committed now more than 80% of what was their pre-staged combat power," the official added.

The official said some Russian soldiers weren't told they were going into combat. The official said "not all of them were apparently fully trained and prepared."

The strong Ukrainian resistance has also hurt morale, according to the official.

Russia has now launched more than 400 missiles on Ukraine, the official said. The U.S. believes Russia has launchers that could be used for thermobaric weapons, but cannot confirm their use, the official said.

Russian forces are making the most progress in the south. Russians are attacking Kherson in south Ukraine, which "appears very much to be contested city at this point," the official said.

Russians are also approaching Mariupol in southeastern Ukraine, and while they haven't yet entered the city, "they are close enough now that they could attack Mariupol with long range fires," the official said.

Two towns on the path to Mariupol are believed to be occupied by the Russians, according to the official.

The U.S. believes the Russians hope to move north out of Mariupol up to the heavily-contested city of Kharkiv. The official said they believe Russian forces are trying to encircle Kharkiv.

The U.S. official noted that they've seen "certain risk-averse behavior by the Russian military" over the last week.

"Take the amphibious assault, for instance. They put those troops ashore a good 70 kilometers away from Mariupol because they knew Mariupol was going to be defended and they could put them ashore in an uncontested environment. And they still haven't reached Mariupol," the official said.

"They are not necessarily willing to take high risks with their own aircraft and their own pilots," the official said.

"And of course we're seeing that on the ground -- the fairly slow and steady progress that they have made, and you guys are seeing it for yourselves on the ground where ... units are surrendering, sometimes without a fight."

-ABC News' Matt Seyler