Ukraine’s interior minister Arsen Avakov has said around 20 “terrorists” and one policeman were killed as armed pro-Russian separatists tried to seize the police headquarters in the eastern port of Mariupol.
The security forces said 60 militants had stormed the headquarters.
The version of events is disputed.
What is certain is that the building was the centre of a pitched battle: it was set ablaze and bodies lay in the streets for several hours afterwards.
But some local people have given a conflicting account: saying the army attacked the police for refusing to disperse activists.
“There was shooting, then a BMP (armoured vehicle) came. They started shooting with heavy calibre weapons, 7.62 calibre and more, heavy automatic machines, we can see the cartridges here,” said a young man at the scene.
The Ukrainian authorities sent reinforcements: interior ministry specialist troops and national guard units.
Some pro-Russian residents tried to stop them. They also blamed the Ukrainian military and extremists from the far-right “Pravy Sector” for the violence.
A member of Ukraine’s parliament, Oleh Lyashko, said eight rebels had been killed in clashes when Ukrainian forces attacked Mariupol’s police headquarters to try to drive out pro-Russian militants.
Ukrainian forces later withdrew from the town, a major industrial centre with a population of about half a million.
Euronews correspondent in Mariupol, Sergio Cantone, said the city had turned into a battlefield for control of southeastern Ukraine.
Travelling from Donetsk, his team passed through three security forces’ checkpoints and roadblocks. The last one at the entrance to Mariupol was controlled by the Ukrainian army.
Speaking outside the fire-damaged police headquarters after the battle, Sergio Cantone said:
“The antagonism in southeastern Ukraine is almost turning into civil war. It’s an intense struggle that will heavily influence the elections, not only (this Sunday’s self-proclaimed) referendum (on independence for the Donetsk region).”