Ukraine forces continued defending the capital of Kyiv on the fourth day of fighting with Russia, while Russian forces penetrated Ukraine’s second-largest city, Kharkiv, and blew up a natural gas pipeline.

"The Russian enemy's light vehicles have broken into Kharkiv, including the city centre," regional Governor Oleh Sinegubov said, according to Reuters. "Ukraine's armed forces are destroying the enemy. We ask civilians not to go out."

Russian troops reportedly blew up the gas pipeline on Sunday, a Ukrainian state agency said. Videos published by adviser to the Ukraine interior minister, Anton Herashchenko, shows tanks moving through the eastern Ukraine city. 

UKRAINE BATTLES RUSSIAN FORCES: LIVE UPDATES

Explosions lit up the sky Sunday outside of Kyiv, where missiles struck the city of Vasylkiv and caused a fire at the oil depot in the village of Kryachky, according to the city's mayor. 

Ukraine servicemen after Russian invasion

Ukrainian servicemen take positions at the military airbase Vasylkiv in the Kyiv region, Ukraine February 26, 2022.   (REUTERS/Maksim Levin)

At least 64 civilians have been killed since Russia entered Ukraine last week, the U.N. Office for the Coordination of Humanitarian Affairs reported Saturday. The office added that the number is likely "considerably higher."

Thousands have been left without electricity or water due to damage to infrastructure, while hundreds of homes have been damaged or destroyed, according to the U.N. office. 

PUTIN ‘FURIOUS’ UKRAINE INVASION HASN’T BEEN ‘EASY,’ EU OFFICIAL SAYS, CITING INTEL REPORT

The United Nations’ refugee agency estimated Sunday that 368,000 Ukrainians have fled the country. The number is expected to continue rising.

Ukraine President Volodymyr Zelenskyy refused the U.S.’s offer on Friday to evacuate Kyiv. He announced early Sunday morning that Ukraine has filed an application against Russia with the International Court of Justice and called for Russia to lose its voting power as a member of the U.N. Security Council. 

Ukrainian President Volodymyr Zelenskyy

Ukrainian President Volodymyr Zelenskyy stands alongside other government officials in a video posted to social media Friday vowing to defend the country from a Russian invasion.  (Armed Forces of Ukraine)

"Russia must be held accountable for manipulating the notion of genocide to justify aggression. We request an urgent decision ordering Russia to cease military activity now and expect trials to start next week," Zelenskyy posted to Twitter. 

Russia sent a delegation to Belarus for peace talks with Ukraine, according to the Kremlin. But Ukraine’s president suggested other locations, saying his country was unwilling to meet in Belarus because it served as a staging ground for the invasion.

UKRAINE SHOWDOWN: VOLODYMYR ZELENSKYY CHALLENGES VLADMIR PUTIN

"We are fighting, fighting for our country, fighting for our freedom because we have the right to do that," Zelenskyy said. "The past night was tough — more shelling, more bombing of residential areas and civilian infrastructure. There is not a single facility in the country that the occupiers wouldn’t consider as admissible targets."

Vladimir Putin

Matt Schlapp doesn’t think Russian President Vladimir Putin would have invaded Ukraine if Trump was in office.  (Yuri Kochetkov/Pool)

Russian President Valdimir Putin is meanwhile allegedly "furious" and "fuming" that his military’s invasion of Ukraine is not going as smoothly as he hoped, according to a European Union official who says he has reviewed a Ukrainian intelligence report. Putin is allegedly watching the invasion of Ukraine from his "lair in the Urals."

CLICK HERE TO GET THE FOX NEWS APP 

Fox News has not independently confirmed the authenticity of the intel report. 

The Associated Press and Fox News’ Dom Calicchio contributed to this report.