Ukrainian Deputy Prime Minister Iryna Vereshchuk said six humanitarian corridors have been agreed with Russian officials and confirmed with the International Committee of the Red Cross to operate during a temporary cease-fire Wednesday.

According to Vereshchuk, the evacuation routes for civilians are open from towns north of Ukraine's capital, Kyiv, where there has been heavy fighting, as well as from the besieged southeastern port city of Mariupol, where an evacuation failed yesterday. Another route goes from the town of Izium near hard-hit Kharkiv, Ukraine's second-largest city, and another from the eastern city of Volnovakha, where civilians have been trying to evacuate for several days. Another route leads from northeastern city of Energodar, where shelling caused a fire at Ukraine's largest nuclear power plant last week.

Vereshchuk said Russian officials had sent a letter to the Red Cross confirming the routes and a cease-fire for Wednesday from 9 a.m. to 9 p.m. local time. She called on Russia to keep to its commitment and not to violate the cease-fire, as she said it did in Mariupol and Volnovakha on Tuesday.

"We ask Russian forces to commit to their obligations and keep the ceasefire till 9 p.m. as agreed," Vereshchuk said in a statement Wednesday morning.

Vereshchuk noted that an orphanage with 55 children and 26 staff also needs to be evacuated from Vorzel, a town just north of Kyiv.

"The evacuation of them will be done as a separate special operation," she said.

The Russian Ministry of Defense said in a statement Wednesday that it has discussed the interaction on the Ukraine track with the Red Cross

-ABC News' Julia Drozd and Patrick Reevell

U.S. President Joe Biden called the parents of Trevor Reed, a former U.S. Marine who has been detained in Russia for nearly three years and whose case has gotten renewed attention amid the Ukraine-Russia conflict.

The president spoke to Joey and Paula Reed after an event in Fort Worth, Texas, on Tuesday, according to the White House.

On the call, the president reiterated his commitment to doing everything he can to bring their son home, to staying in close touch with them through his national security team and to finding a time to meet in person, the White House said.

A Reed family spokesperson also confirmed to ABC News that Biden called them to apologize for not being able to stop and meet them in person.

The family says they have been asking to meet with the president for several months to help free Reed, a Texan who they say has been denied treatment for suspected tuberculosis, and specifically asked to meet the president in Texas on Tuesday but were denied.

Reed and another former Marine, Paul Whelan, have spent years in Russian custody on charges that their families and American officials say were fabricated by Russia in order to seize them as bargaining chips.

-ABC News' Sarah Kolinovsky and Conor Finnegan

Ukrainian President Volodymyr Zelenskyy thanked U.S. President Joe Biden for additional sanctions taken against Russia on Tuesday, saying they will "significantly weaken the occupiers."

The new measures include a ban on imports of oil, petroleum products, gas and coal from Russia. U.S. citizens are also now prohibited from investing in Russia's fuel and energy sector.

"A ban on oil imports to the United States will weaken the terrorist state economically, politically and ideologically, because it is about freedom -- about the future, about where the world will move," Zelenskyy said, adding that he is "personally grateful" to Biden.

Zelenskyy also expressed gratitude to U.K. Prime Minister Boris Johnson for instating a similar ban, describing Johnson as "a man of his word, a sincere friend of Ukraine."

-ABC News' Christine Theodorou

Even with a series of harsh measures already taken on Russia, including a ban on Russian imports, the sanctioning of Russia’s central bank and the enactment of export controls, the U.S. could enact even tighter sanctions, several experts told ABC News.

The U.S. could push other countries to make commitments to decrease their reliance on Russian energy -- which it and the U.K. are already beginning to do -- and to increase their own production of oil and gas to lower the high energy prices Americans and Europeans are starting to face — and it could also get Saudi Arabia, Venezuela and others to increase their exports.

Other current sanctions the U.S. could tighten include imposing "full-blocking" sanctions, the harshest possible financial sanctions, on Sberbank, Russia’s largest bank. The U.S. has already done this for several other banks but has only put limited restrictions on Sberbank in order to limit the impact on the ordinary Russians who use the bank.

The U.S. could also put additional secondary sanctions on banks, put more restrictions on Russian goods, keep pursuing oligarchs and other Russian elites and sanction other Russian sectors such as minerals, chemicals, and coal.

The sanctions the West has already imposed have devastated the Russian economy at a rapid clip. They will continue to compound and inflict more pain on the Russian economy as they continue to play out, the experts said.

-ABC News' Ben Gittleson

The tower that provides the main signal to TV and radio in Kyiv has been struck by a Russian missile, leaving at least five dead, Ukrainian officials said.

Ukraine's Foreign Minister Dmytro Kuleba tweeted that the tower "is situated on the territory of Babyn Yar. On September 29-30, 1941, Nazis killed over 33 thousand Jews here. 80 years later, Russian Nazis strike this same land to exterminate Ukrainians. Evil and barbaric."

Ukraine's President President Volodymr Zelenskyy tweeted, "What is the point of saying «never again» for 80 years, if the world stays silent when a bomb drops on the same site of Babyn Yar? At least 5 killed. History repeating."

-ABC News' Christine Theodorou