Soldiers picking through charred debris scattered near the smouldering remains of a truck and a few civilians taking fresh air before a curfew were among scarce signs of life in Ukraine's capital on Saturday, after a second night of artillery barrages.

Russian forces have been pounding the centuries-old capital Kyiv and other cities with cruise missiles and shells since the start of an invasion on Thursday morning.

Many shops were closed, including those selling food, and the streets were empty except for a odd car - a contrast to the columns of vehicles choking roads in recent days as tens of thousands of residents fled west - and a few pedestrians pulling suitcases.

"I was smart enough to stock food for at least a month, we have everything," said Serhiy, a middle aged man who said he started buying extra groceries for his family well before the violence broke out.

"I did not trust politicians that this would end peacefully," Serhiy said, taking a walk before a curfew that kicked in at 5:00 p.m.

Four heavily armed soldiers manned a checkpoint near a government building. Amid reports of Russian saboteur groups in the city, passengers in cars were required to keep their hands in the open and show identification papers without sudden moves, a Reuters team reported.

A missile hit a residential building and shelling and gunfire was heard early on Saturday across the city that is home to around 3 million people and was previously extensively damaged during a Nazi German assault in 1941.

Soldiers near a Kyiv train station inspected the still smoking remains of a truck that appeared to have been carrying ammunition and had scattered burnt shrapnel across a highway. Other soldiers dug trenches.

One elderly man inspected the twisted wooden frames of the windows of his house, the glass blown out. He said he was worried a nearby metro station would be targeted. Soldiers stopped residents from entering the metro system, which will now be used for shelter from the fighting rather than for transport.

MILITIAS

In addition to the regular soldiers, on the outskirts of the city, men armed with assault rifles and wearing yellow arm bands could be seen preparing to fight as Russian forces approached.

Some wore civilian clothes and carried hunting rifles, others apparently from neighbourhood militias and other reservist groups had camouflage outfits and professional equipment.

Further out of town, Ukrainians lined up at gasoline stations and bank ATMs, despite government-imposed limits on petrol sales and cash withdrawals.

In Koncha Zaspa, just south of Kyiv, people lined up to collect water from a public pump and to buy food in a local supermarket.