A humanitarian corridor will open out of the besieged city of Mariupol in southeast Ukraine on Friday, the Russian Defense Ministry said.

The corridor, leading to Zaporizhzhya, will be provided by the Russian army at 10 a.m. Moscow time, according to Mikhail Mizintsev, the head of Russia's National Defense Control Center.

The announcement comes following "personal requests" by French President Emmanuel Macron and German Chancellor Olaf Scholz, Mizintsev said in a statement.

"For this humanitarian operation to be successful, we suggest it be conducted with direct participation by representatives from the UN High Commissioner for Refugees and the [International Committee of the Red Cross]," he said.

Russia had previously announced a localized cease-fire in the bombed-out port city to allow civilians to be evacuated Thursday. About 631 residents of the bombed-out city were subsequently able to evacuate in private cars, according to a Ukrainian official. Dozens of buses reserved to drive them out failed to make it into the city, the official said.

A number of previous attempts to establish humanitarian corridors out of Mariupol have failed.

The U.S. government has intelligence that shows some Russian senior officials "likely disagreed" with Russian President Vladimir Putin's decision to invade Ukraine, a U.S. official told ABC News.

"Their disillusionment is probably amplified by the Russian military's underperformance, which includes many friendly fire casualties, including shoot-downs of Russian aircraft by Russian air defense, wide-scale missile launch failures, and stiffer than expected resistance from the Ukrainian people," the official said.

The information is based on a declassified assessment from earlier this month, a source familiar with the intelligence told ABC News.

White House Communications Director Kate Bedingfield told reporters this intelligence speaks to a “larger sense that this has been a failure for Russia."

"I think we've seen reporting that morale amongst the Russian military is low and I think that would not come as a surprise to anyone who's seen what the Russian military is, is enduring here," Bedingfield said during a press briefing Thursday afternoon.

-ABC News' Mary Bruce and Justin Gomez

About 631 residents of the bombed-out city of Mariupol in southeast Ukraine were able to evacuate on Thursday, according to a Ukrainian official.

Ukrainian Deputy Prime Minister Iryna Vereshchuk said the residents fled the city in private vehicles after 45 buses reserved to drive them out failed to make it into the city. Vereshchuk said another 600 civilians still in Mariupol plan to try to evacuate again on Friday.

Ukrainian President Volodymyr Zelenskyy said Thursday in an address to lawmakers of Australia, the Netherlands and Belgium that more than 90% of all buildings in Mariupol have been completely destroyed by Russian strikes.

"Thousands of peaceful Mariupol residents died, people are buried just in the city, in the courtyards of high-rise buildings, or rather, what is left of the high-rise buildings," Zelenskyy said.

-ABC News' Christine Theodorou

About 500 Ukrainian refugees were camped out Thursday outside the port of entry in Tijuana, Mexico, waiting to get into the United States after taking a circuitous route out of their war-torn country more than 10,000 miles away.

The number of Ukrainian refugees at the U.S. southern border entry point grew overnight from about 200 on Wednesday.

Immigration attorneys and humanitarian groups told ABC News that more and more Ukrainians have been showing up at the U.S. border this week, many of them getting there by flying to Mexico City, Mexico, and either taking a connecting flight to Tijuana or driving there.

Among the campers are also many Russians who oppose Russian President Vladimir Putin's decision to invade Ukraine, some telling ABC News they believe they would have been killed had they stayed in their homeland.

Ukrainians have asked for asylum in the United States and in many cases, have been allowed into the country under an exemption to Title 42, the federal policy that halted asylum claims during the pandemic. Some of the refugees allowed in the United States are being housed in San Diego, while others have spread out across the country.

The Russians, on the other hand, are being told they have to first be taken into the custody of the .S. Immigration and Customs Enforcement as their requests to enter the country are considered.

Humanitarian groups are questioning the handling of the Ukrainians and Russians at the border versus all the other migrant groups fleeing horrific situations, including those coming from Haiti and Central America.

-ABC News' Will Carr

All Russian troops have left the Ukrainian cities of Kyiv and Chernihiv, withdrawing north toward the borders of Belarus and Russia to consolidate before likely redeploying to the Donbas region in eastern Ukraine, a senior U.S. defense official told reporters Wednesday.

But even with the Russians gone, the territory remains treacherous.

"There are some indications that they left behind mines and things like that, so the Ukrainians are being somewhat careful in some areas north of Kyiv as they begin to clear the ground and clear the territory and re-occupy it," the official said.

While the U.S. hasn't yet seen these troops redeploy elsewhere in Ukraine, it'll likely happen soon, according to the official. Ukrainian forces are preparing for a major fight in Donbas, the official said.

The official also said the Pentagon is "monitoring" an apparent nitric acid explosion in Ukraine's Luhansk region, which Russia blamed on Ukraine.

"We've seen the Russians claim that this was a Ukrainian attack on this. We do not believe that is true," the official said. "We do believe that the Russians are responsible, but exactly what they used when they did it, why they did it, what the damage is, we just don't have that level of detail," the official said.

The official also noted that a small number of Ukrainians currently in the U.S. for "professional military education" were pulled aside for a couple days of training on Switchblade drones, which the U.S. is sending overseas as part of its military aid, according to the official.

"Although it's not a very difficult system to operate, we took advantage of having them in the country to give them some rudimentary training on that," the official said.

-ABC News' Matt Seyler