(NewsNation) — Ukraine accused Russian forces of killing seven civilians in an attack on women and children trying to flee fighting near Kyiv on Saturday as fighting continued on the capital city’s outskirts.

Officials said heavy shelling and threats of Russian air attacks were endangering attempted evacuations of civilians from encircled towns and besieged cities.

Ukrainian President Volodymyr Zelenskyy said Russia sent in new troops after Ukrainian forces had put 31 of its battalion tactical groups out of action in what he called Russia’s largest army losses in decades. He gave no details.

Zelenskyy is demanding the release of Ivan Fedorov, the mayor of Melitopol, after surveillance video showed him being marched out of city hall apparently surrounded by Russian soldiers.

Zelenskyy has accused Russia of kidnapping the mayor, calling the abduction “a new stage of terror.” The Biden administration had warned before the invasion of Russian plans to detain and kill targeted people in Ukraine, with Zelenskyy himself likely the top target.

Zelenskyy said he spoke to German Chancellor Olaf Scholz and French President Emmanuel Macron about pressuring Russia to release Fedorov.

More than 2,000 residents of the southern city, which is now under Russian control, protested outside the city administration building to demand Fedorov’s release, Kyrylo Tymoshenko, an aide to Zelenskyy, said.

The call between Scholz, Macron and Russian President Vladimir Putin took place Saturday.

During the 75-minute conversation, the chancellor and the French president urged an immediate ceasefire in Ukraine and a diplomatic solution to the conflict, according to a spokesperson for Scholz.  It was agreed they would not disclose any further content of the conversation.

Zelenskyy said he’d be open to talks with the Israeli Prime Minister as well.

Russia has not commented on the fate of Fedorov, who Ukrainian officials said was kidnapped by Russian forces on false accusations of terrorism.

Russian forces have captured the eastern outskirts of the besieged city of Mariupol, Ukraine’s military said.

In a Facebook update, the military said the capture of Mariupol and Severodonetsk in the east were a priority for Russian forces.

Putin launched the invasion on Feb. 24 in an operation that has earned nearly universal condemnation worldwide and drawn tough Western sanctions on Russia.

The invasion has trapped thousands of people in besieged cities and sent at least 2.5 million Ukrainians fleeing to neighboring countries. One who spoke to NewsNation named Tatiana who was headed to Poland with her 10 children said despite everything, she couldn’t be more proud to be Ukrainian.

“I’m very thankful for the people who help us,” she said. “One of them helped us to get to the train, others help us here. Everyone is united.”

Mariupol has been under a two-week siege, with no electricity, gas or water. Repeated efforts to evacuate people from the city of 430,000 have fallen apart as humanitarian convoys come under shelling.

Video shot by an Associated Press journalist shows a Russian tank firing shells at an apartment block in Mariupol. Medical worker Anastasia Erashova was shot in the hip by sniper fire, and one of her children had been killed by shells.

“We came to my brother’s (place), all of us together. The women and children went underground and then some mortar struck that building. We were trapped underground, and two children died. No one was able to save them,″ she said through tears. “I don’t know where to run to. Who will bring back our children? Who?”

Zelenskyy said Ukraine could not stop fighting but was upholding a ceasefire around an agreed humanitarian corridor out of Mariupol and called on Russia to do the same.

Amin Awad, the U.N.’s crisis coordinator for Ukraine, said Saturday that the global body is seeking agreement with both sides in the conflict to establish corridors for delivering much-needed aid.

He said progress is being made on the corridors and accompanying ceasefires but expressed frustration over resistance to implementing them quickly.

Awad said overall, as many as 12 million Ukrainians may need aid.

Moscow has previously blamed Kyiv for failed evacuations.

At least 579 civilians have been killed in Ukraine since the start of the war, and more than 1,000 have been injured, according to the U.N. human rights office.

The Geneva-based office had documented 564 civilian deaths and 982 injured a day earlier.

It said most recorded civilian casualties were caused by the use of explosive weapons with a “wide impact area,” such as shelling from heavy artillery and missile strikes.

U.N. officials said they believe the actual number of casualties is considerably higher than what’s so far been recorded because the receipt of information has been delayed and many reports still need to be corroborated.

The Office of the U.N. High Commissioner for Human Rights said Saturday that 42 of those killed were children, while 54 were injured.

At least 79 children have been killed and nearly 100 have been wounded since the start of the Russian invasion, the Ukrainian chief prosecutor’s office said Saturday.

In a statement, the office said most of the victims were in the Kyiv, Kharkiv, Donetsk, Sumy, Kherson and Zhytomyr regions. However, it noted that the numbers aren’t final because active fighting continues.

The prosecutor’s office also said that more than 280 educational institutions have been hit and nine of them have been completely destroyed, depriving large numbers of students of access to education.

Another Russian general has been killed in the fighting, according to Ukrainian officials.

Anton Gerashchenko, an adviser to Ukraine’s Interior Ministry, said Saturday that Russian Maj. Gen. Andrei Kolesnikov was killed in action during the fighting over Mariupol. He would be the third Russian general to die in the war, according to Ukrainian officials.

The Russian military, which has kept a tight lid on information about its losses, didn’t confirm Kolesnikov’s death.

Previously, unofficial Russian sources confirmed the death of one Russian general.

The death of Maj. Gen. Andrei Sukhovetsky, the commanding general of the Russian 7th Airborne Division, was confirmed by his colleague and the officers’ association in southern Russia. The death of another general, Maj. Gen. Vitaly Gerasimov, wasn’t confirmed by any Russian sources.

The Associated Press and Reuters contributed to this report.