Russian soldiers have seized several Ukrainian army vehicles and are heading towards the center of the capital Kyiv, a top Ukrainian defense official said on Friday, Ednews reports citing Anadolu Agency.

On social media, Deputy Defense Minister Anna Malyar said Russian soldiers had seized two Ukrainian vehicles as well as Ukrainian soldiers' uniforms and are advancing towards the Kyiv city center from Obolon, a northern residential district of the capital some 12 kilometers (7.5 miles) from the center.

"A convoy of Russian military trucks are following them. They will surely be neutralized," Malyar added.

Separately, according to a Ukrainian General Staff statement, the Ukrainian Air Force is protecting the skies of Kyiv, and since 4 a.m. (0200GMT) Ukraine's air defense system has blocked rocket attacks on the capital.

Sirens and several explosions were heard early Friday in both Kyiv and Lviv, a city in western Ukraine some 540 km (336 mi) from the capital.

Ukrainian Foreign Minister Dmytro Kuleba said there was "horrific Russian rocket strikes on Kyiv."

"Last time our capital experienced anything like this was in 1941 when it was attacked by Nazi Germany," he said on Twitter early Friday.

"Ukraine defeated that evil and will defeat this one. Stop Putin. Isolate Russia. Severe all ties. Kick Russia out of everywhere," he added.

There were also local reports of downing a warplane over Kyiv, which was initially thought to be a Russian aircraft but later announced to be a Ukrainian plane.

In addition to airstrikes, Russia is also pressuring the city on the ground as the Ukrainian army blew up three bridges around Kyiv to stop the advance of Russian tanks.

Anton Gerashchenko, advisor to the Ukrainian interior minister, stated that a tank convoy of Russian military units was about to enter the capital via Ivankiv and Chernihiv.

"Today is going to be a very difficult day," Gerashchenko said, adding that Russian tanks could be destroyed with anti-tank weapons of Ukraine.

Meanwhile, US officials stated that Russian troops are currently only 30-35 km (20-21 mi) away from Kyiv.

Following a months-long military buildup around neighboring Ukraine's borders, Russian President Vladimir Putin announced the intervention into Ukraine on Thursday. It has been met by international condemnation and announcements of new sanctions by Western countries.