Fragments from downed Russian missiles started a fire that killed at least two people and injured eight others in Kyiv, on Saturday, according to Ukrainian officials.

A Telegram post from Serhiy Popko, the head of Kyiv's military administration, revealed that falling debris caused a fire on several floors of a 24-story apartment building in a central district, The Associated Press reported.

More than 20 missiles were detected and taken down by anti-aircraft units, Popko said. Video of the scene appeared to show the upper floors of the building on fire and the parking lot covered with ash and debris.

About 40 cars in the parking lot were damaged in the incident, he said.

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Kharkiv and other Ukrainian cities were also hit by missiles early on Saturday as residents throughout the country heard air alerts, Reuters reported.

At least three Russian missiles targeted Kharkiv, Ukraine's second-biggest city, and one of them started a fire after striking a gas line, according to Mayor Ihor Terekhov. He said emergency services were at the scene, but did not disclose the number of casualties – if any.

The mayor of Dnipro, a city in eastern Ukraine, also reported damage as eight private homes were destroyed in an attack.

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Anti-aircraft units were active throughout the country, the Ukranian military said. 

Air alerts were lifted for most of the country after about an hour.

The Associated Press and Reuters contributed to this report.

After calling for an armed rebellion to remove Russia's defense minister, Wagner Group chief Yevgeny Prigozhin, announced Saturday morning that he and his troops reached the city of Rostov-on-Don.

Prigozhin posted confirmation of his arrival in the city, which is home to the Russian military headquarters overseeing the war in Ukraine, in a social media video, according to The Associated Press.

In the video, he claimed that his forces had taken control of military facilities in Rostov-on-Don, including the air field. Other videos posted on social media showed military vehicles and tanks on the streets.

It was not immediately clear how he entered the city, which is under heightened security following Prigozhin's threat, or how many troops he brought with him.

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Despite Wagner playing a crucial role in Russia's invasion of Ukraine, Prigozhin has been feuding with the defense ministry, accusing Russian military officials of starving his troops of weapons and ammunition.

In a series of angry video and audio recordings on Friday, Prigozhin accused Russian Defense Minister Sergei Shoigu of ordering a rocket strike on the private military contractor's field camps where the group is fighting on behalf of Russia in Ukraine.

"This is not a military coup, but a march of justice," Prigozhin declared. "The evil embodied by the country’s military leadership must be stopped."

Prigozhin then referred to Shoigu as "scum" and said he "will be stopped."

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According to state news agency Taas, the National Anti-Terrorism Committee, part of the Federal Security Services, will be opening a criminal investigation into Prigozhin on charges of calling for an armed rebellion. The report states that Russian President Vladimir Putin was kept informed of the situation.

Moscow appeared to be take the threat seriously, as the National Guard and riot police were sent to provide security for key facilities in Moscow, which includes transport infrastructure and government agencies, according to Taas.

Fox News Digital's Adam Sabes and The Associated Press contributed to this report.