Russia pressed its invasion of Ukraine to the outskirts of the capital on Friday after unleashing airstrikes on cities and military bases and sending in troops and tanks from three sides in an attack that could rewrite the global post-Cold War security order.
Explosions sounded before dawn in Kyiv and gunfire was reported in the city centre as Western leaders scheduled an emergency meeting.
Among the signs that the Ukrainian capital was increasingly threatened, the military said that a group of Russian spies and saboteurs was seen in a district of Kyiv about 5 kilometres (3 miles) north of the city centre. Police told people not to exit a subway station in the city centre because there was gunfire in the area.
Meanwhile, Ukraine's president pleaded for international help to fend off an attack that could topple his democratically elected government, cause massive casualties and ripple out damage to the global economy.
Ukrainian officials said a Russian aircraft had been shot down and crashed into a building in Kyiv overnight, setting it ablaze and injuring eight people.
Meanwhile, air raid sirens wailed over the city of 3 million people, where some were sheltering in underground metro stations and bunkers.
Windows had been blasted out of a 10-storey apartment block near Kyiv's main airport, where a two-metre crater filled with rubble showed at the place a shell had struck before dawn. A policeman said people were injured there but not killed.
Russian-backed separatist leaders expect their troops to move outwards to the borders of Ukraine's Donetsk and Luhansk regions very soon, Russian news agencies quoted separatist leaders as saying on Friday.
The separatists – whose independence Moscow recognised this week – currently control only parts of those provinces.
Ukraine's nuclear agency said on Friday it was recording increased radiation levels from the site of the defunct Chernobyl nuclear power plant.
Experts at the agency did not provide exact radiation levels but said the change was due to the movement of heavy military equipment in the area lifting radioactive dust into the air.
Russia launched its invasion by land, air and sea on Thursday following a declaration of war by Putin, in the biggest attack on a European state since World War Two.
Putin says Ukraine is an illegitimate state carved out of Russia, a view Ukrainians see as an attempt to erase their more than thousand-year history.
