Seven European OSCE inspectors were freed yesterday in a flashpoint town in east Ukraine, where surrounded pro-Moscow rebels are battling a fierce military assault amid a soaring national death toll.
The unexpected release was a bolt of good news in Ukraine's startling descent into chaos, after a bloody day in which more than 50 people died -- most of them in a horrific inferno in the southern city of Odessa.
But the international crisis over Ukraine deepened, with Russia saying it would now be "absurd" for the ex-Soviet republic to hold a planned May 25 presidential election.
That opened the risk of sweeping US sanctions against Russia after President Barack Obama warned of punishment if perceived Moscow meddling scuppered the poll.
Meanwhile, on the outskirts of Slavyansk, where the OSCE team was held, AFP journalists witnessed a ferocious firefight between Kalashnikov-armed insurgents and soldiers outflanking their checkpoint.
One man was shot dead and lay in the road, while a fatally wounded driver gasped for breath at the wheel of his car, said the journalists, who were briefly pinned down between both sides. Armoured vehicles fired occasional heavy-calibre rounds at the outnumbered insurgents.
At least nine people died the day before around Slavyansk, when the military tightened its noose on the town but lost two helicopter gunships to shoulder-launched missiles in the process.
All of Ukraine was reeling yesterday at news of 42 deaths the day before in the southern city of Odessa, where pro-Russian and pro-Kiev militants clashed savagely and repeatedly.
Most of the deaths -- many believed to be pro-Russians -- occurred in a trade union building set alight as each side lobbed Molotov cocktails at the other.
Acting president Oleksandr Turchynov declared two days of mourning over the loss of lives across the country.
Russia slammed the violence and blamed it on Kiev and on ultranationalists it says make up Ukraine's new Western-backed government.
The Kremlin added that Russia had lost any influence it had over the armed separatists, and that it had received "thousands of calls" from eastern Ukraine requesting "active help".
Russian President Vladimir Putin -- whom the West sees as masterminding Ukraine's insurgency despite his denials -- has kept an estimated 40,000 of his troops massed on Ukraine's border for the past two months. He has said he "very much hopes" he will not have to order them to invade.