The simmering conflict between Moscow’s military leadership and Yevgeny Prigozhin, the bombastic chief of private mercenary group Wagner, has dramatically escalated into an open insurrection that plunges Russia into renewed uncertainty.

Moscow's mayor said the capital is reinforcing security as Prigozhin claimed to have seized control of key military facilities in the Russian cities of Rostov and Voronezh Saturday.

Here's the latest:

Wagner claims control in Rostov: Prigozhin said in a video he is in Rostov-on-Don, in southern Russia close to the Ukraine border, and that his forces have control of military facilities and the airfield there. He pledged to blockade Rostov and move on to Moscow if Russia's Defense Minister and top general did not meet with him in the city, where Russia’s Southern Military District is headquartered. He said his men are not stopping the officers from carrying out their duties. It comes after Prigozhin said his fighters were entering the Rostov region on Friday and that Russian Guards and military police have joined the Wagner group. Videos circulating on social media and geolocated to Rostov city show military vehicles on the streets and helicopters over the city Saturday morning. It is currently unclear whose command the vehicles are under the control of.

Claims of control in Voronezh: The Wagner group later said it had taken control of Russian military facilities in the city of Voronezh, in southwestern Russia, saying "the army switches to the side of the people." Earlier, the governor of Voronezh oblast said that "a convoy of military equipment is moving along the M-4 Don Federal Highway." The M-4 is a highway connecting Voronezh and Rostov-on-Don. Voronezh is directly north of the Rostov region.