Fierce fighting between Ukrainian government forces and pro-Russia protesters today in Mariupol killed seven people, turned police headquarters into a smouldering ruin and left the city centre blocked off after residents built barricades of tires.
The violence in the strategic port city on the Azov Sea - along the main road between the Russian border and the Crimean Peninsula - was a clear sign of increasing unrest in eastern Ukraine.
The Donetsk region, which includes Mariupol, and the neighbouring Luhansk region are to hold a hastily organised referendum on Sunday on declaring sovereignty, a move likely to deepen the crisis between supporters of Ukraine's fledgling government and pro-Russia insurgents who claim the authorities in Kiev are a fascist junta.
There were varying accounts of today's violence in Mariupol, a city of a half-million people that also was hit by unrest last month.
Ukrainian Interior Minister Arsen Avakov said about 60 gunmen attacked the police station and were repulsed in an operation that killed one policeman and about 20 people that he called "terrorists".
The Donetsk regional government said that as of 8pm, seven people were killed and 39 others were wounded in the violence that came on the day that commemorates the 69th anniversary of the defeat of Nazi Germany.
The conflicting death tolls could not be reconciled. A reporter saw three bodies on the street - one of them covered by a blanket with a policeman's hat placed at the head.
As the police station burned, residents gave accounts of the day's events that contradicted the official line. Some said government troops fired on unarmed protesters and attacked police who were protecting demonstrators occupying the nearby administration headquarters.
Amateur video on the Internet showed soldiers firing warning shots and later wounding men who angrily confronted them. At least one man in civilian clothes could be seen shooting in the direction of the soldiers, who backed away on foot.
Larissa Gremacheva, a retired woman, said soldiers fired on unarmed men.
"They began to shoot, and with my own eyes I saw how one man was wounded in his leg and another in his arm," she said.
Government troops appeared to have lost an armoured personnel carrier to attacking mobs. In the evening, several youths - apparently drunk - were seen in the city centre climbing onto the vehicle and trying but failing to start its engine.
By nightfall, all government forces had abandoned the city centre, which was blocked off with barricades of tyres.
US State Department spokeswoman Jen Psaki condemned the violence, which she said was "caused by pro-Russia separatists".
"We continue to call for groups who have jeopardised public order by taking up arms and seizing public buildings in violation of Ukrainian law to disarm and leave the buildings they have seized," she said.
Last month, Mariupol's city hall had been occupied for more than a week by pro-Russian protesters who were armed and masked. On April 16-17, three people were killed and 12 injured after about 300 protesters armed with stun grenades and firebombs tried to seize a National Guard base.