KYIV — The sound of gunfire has echoed through Ukraine's capital, Kyiv, as Russian tanks were filmed entering the city for the first time.

Ukraine's Ministry of Defense called on those living in Kyiv's northern outskirts — where the tanks were filmed — to make firebombs "to neutralize the enemy".

Overnight, the city was hit by blasts, with at least one block of flats damaged and several civilians injured.

Russia has denied carrying out strikes.

The unnamed source at Russia's defense ministry also said a plane shot down over Kyiv was Ukrainian, Reuters news agency reports. Ukraine has said the jet was Russian.

As the second day of fighting began, Moscow - which is attacking from the east, north and south - appeared to have Kyiv firmly in its sights.

Clashes have been reported between the two sides, with Ukrainian forces blowing up a bridge in an attempt to slow Russia's advance. Western intelligence officials warned earlier that Russia was building an "overwhelming force" to take control of the city.

Citizens in the northern Obolon district were told to stay at home to avoid "active military operations" by city officials on Friday, Reuters adds. Obolon is the same area where it appeared tanks were filmed earlier in the day.

The Ministry of Defence had already appealed to the district's residents on its Facebook page to "inform us of troop movements, to make Molotov cocktails [firebombs] and neutralise the enemy".

Overnight, families took shelter in Kyiv's metro stations as aerial attacks struck the city, including the densely populated Pozniake area, injuring at least eight.

"Putin, we want to see you slaughtered like an animal," one Kyiv resident told the BBC's Nick Beake.

"How we can live through it in our time?" Oxana Gulenko asked Reuters as she cleaned up broken glass from one blast. "What should we think. Putin should be burnt in hell along with his whole family."

Sergei Lavrov, Russia's foreign minister, said Moscow was ready for talks "as soon as the armed forces of Ukraine respond to our call and lay down their arms".

He told reporters Russia did not intend to occupy Ukraine, saying their aims were clear: "Demilitarisation and de-Nazification."

Ukraine's President Volodymyr Zelensky had earlier said Russia was seeking to "destroy Ukraine politically by destroying the head of state".

"According to the information we have, the enemy has designated me as target number one. My family is target number two," he said.

President Zelensky has vowed to stay in Kyiv and to continue fighting the attacks across Ukraine - which is coming from the north, south and east - ordering the call-up of conscripts and reservists in all of Ukraine's regions. The country's defense minister urged anyone able to hold a weapon to join the effort to repel Russia.

There have already been stories of immense bravery in the face of stark odds - including that of 13 border guards on a tiny island in the Black Sea who refused to surrender to a Russian warship and were massacred in a bombardment.

President Zelensky said they would be given posthumous war hero honors.

Thursday also saw fighting around the site of the former nuclear power plant in Chernobyl. Ukrainian presidential adviser Mykhaylo Podolyak said the nuclear site itself had been lost following a "fierce battle".

On Friday, Ukraine's nuclear agency said it was recording raised radiation levels in the area. A statement released by Russia's Ministry of Defence said levels were normal, adding an agreement had been reached "to ensure security of the power plant and sarcophagus of the Chernobyl Nuclear Plant".

Ukraine says at least 137 people — civilians and soldiers — have been killed, while British Defence Minister Ben Wallace said the UK estimated that Russia had lost 450 personnel since Moscow launched the offensive in the early hours of Thursday morning, after weeks of escalating tensions.

President Vladimir Putin — who declared war in a dramatic televised address — has threatened any country attempting to interfere with "consequences you have never seen".

The UK, EU and other allies vowed to impose tough new sanctions to punish Moscow, but said they would not send in troops.

French President Emmanuel Macron held a telephone call with his Russian counterpart, in what was Mr Putin's first conversation with a Western leader in days, demanding an "immediate halt" to the offensive. The Kremlin, however, simply said the pair had a "serious and frank exchange of views". — BBC