A dead man in civilian clothes lay sprawled on the sidewalk of a residential neighbourhood in northern Kyiv on Friday, as Ukrainian soldiers took up positions under the cover of a two-story building.

Two dozen metres away, medics were rushing to help another man, who had been driving a civilian car that was completely crushed under the tracks of an armoured vehicle.

An advance party of Russia's invasion force left a trail of damage in its wake as clashes erupted inside Ukraine's capital Kyiv for the first time, amid rising fears the city is about to be stormed or come under siege.

Pedestrians ran for safety as small arms fire and explosions erupted in the Obolonsky district in the city's north.

The larger blasts could be heard in the city centre, where residents endured a first tense night under curfew and the sounds of bombing.

Eyewitnesses said they saw corpses of what looked to be two dead Russian soldiers near the truck, but the Ukrainian military, who were inspecting the wrecked car, did not allow AFP to come closer.

"Two infantry fighting vehicles with hidden identification marks were driving along the road. I didn't see the unit insignia," said civilian Yevgen Nalutay, 39.

"One hid right in the underpass and the other went further along the road, but then turned into the courtyard of the house and I didn't see him further. People were fleeing."

Resident Viktor Berbash, 58, told AFP he ran out to his balcony after he heard shooting on Friday morning.

Ukraine's leader has accused Russia of deliberate targeting civilian areas in missile strikes as the battle arrives in Kyiv
Ukraine's leader has accused Russia of deliberate targeting civilian areas in missile strikes as the battle arrives in Kyiv AFP / Daniel LEAL

"I saw an armoured vehicle and there was automatic fire. And here this car, with probably an anti-aircraft gun on it, was already here."

He watched as the civilian in a car was crushed by a tank -- an intentional move, he said -- unsure if the driver survived or not.

"Two armoured vehicles were driving along the road, and the second of them deliberately drove into the oncoming lane," he said.

"It was not by chance, it was for fun, there was no need for this. And it just ran into this car. Stopped, reversed over it again and drove on."

The Ukrainian ministry of defence said the clash had been provoked by "an enemy sabotage and reconnaissance group".

Russian forces first arrived on the outskirts of Kyiv on Thursday when waves of helicopter-borne troops assaulted the Gostomel airfield just outside the city, close to Obolonsky.

The Ukrainian military claims to have repulsed the attack on the airbase, but Russian ground forces have also been pushing down the west bank of the Dnieper river from Belarus.

As the reconnaissance party arrived in Obolonsky, the Ministry of Defence called on civilians to resist.

"We urge citizens to inform us of troop movements, to make Molotov cocktails, and neutralise the enemy," it said in an online posting.

The fighting on the broad highways and in between the densely inhabited multi-storey apartment blocks of northern Kyiv may be an omen of what is to come if Russian forces assault the city of some three million people.

President Vladimir Putin appears intent on overthrowing the Ukrainian government, and Western intelligence expect his forces to descend on the capital within hours or days.

Overnight ballistic missiles were fired at targets within Kyiv ahead of what Washington warns will be a Russian operation to "decapitate" President Volodymyr Zelensky's administration.