Shrouded in smoke and tear gas and echoing with the din of stun grenades and drums, the centre of Kiev turned into a battle zone amid deadly clashes between security forces and protesters.
Police launched the first assault against stone-throwing protesters in the morning, marching forward as a military formation clad in body armour with their shields in front.
Protesters stepped up their attacks, flinging stones and Molotov cocktails but could do little against the tear gas and stun grenades used by the elite Berkut riot police who also fired rubber bullets.
Five activists were killed as a result and 300 wounded Wednesday, the medical centre of the protest movement said.
Hundreds of hardcore protesters regrouped after being pushed from the main scene of the clashes, burning tyres in a bid to create a new barricade and filling the air with rancid black smoke.
Further raising the stakes, police then moved an armoured personnel carrier into the protest zone even as President Viktor Yanukovych was meeting opposition leaders.
Later in the evening, the protesters built a protective front line of burning tyres, whose flames lit up the night sky and whose smoke billowed into the air and was visible from all over Kiev.
The capital, which successfully hosted the final of the Euro 2012 football championships, was turned into a virtual war zone as demonstrators scattered, chased by security forces.
The street cafes on Kiev's famed Khreshchatyk Avenue nearby were all closed as the clashes intensified.
January 22 is supposed to be the country's day of national unity, remembering the unification of western and eastern Ukraine in an attempt at independence during the turbulence of 1919.
However Ukrainians seemed less unified than ever amid the carnage on the street, with the mainstream opposition leaders apparently having lost any authority over the most radical protesters.
Five activists were killed, according to the medical service of the protest movement. Four of the five people found dead had gunshot wounds,according to the Ukrainska Pravda new website.
The clashes were restricted to an area in the centre of the capital by Grushevsky Street, the scene of three days of violence that have raised tensions from two months of protests to a new peak.
So far, the security forces have not moved against the main protest camp on Independence Square in Kiev, known locally as the Maidan, where thousands were now gathering to show the strength of the protest.
"We are here to protect the Maidan. Our children are behind us. Our future is in front of us," said protester Bogdan Shkur, 50.
Following rumours that a police move against the centre of the clashes was imminent, many of the protesters were wearing flak jackets and carrying ad hoc weapons like baseball bats and sticks.
AFP photographers saw two protesters firing guns but it was not immediately clear from where such weapons had been obtained.
They had also tried to match the riot shields of the police by manufacturing their own shields out of scrap metal.
The streets were turned dark by the soot from burning wreckage mixed with the white of the snow falling on a freezing cold day that is likely to be remembered in Ukraine forever.
Former interior minister Yuriy Lutsenko, a protest figurehead who spent over two years in prison under Yanukovych, sought to speak directly to the riot police and persuade them to change sides.
"You're protecting with your bodies the gang who robbed the country. You used to be the country's pride, but there's mafia behind your backs now," he said.
Ukrainians have until now always boasted that the country, for all its problems, had no inclination for violence and the 2004 Orange Revolution succeeded without even a single window being broken.
But this illusion has now been shattered.