A protester walks past a burning pro-Russian tent camp near the trade union building in Odessa May 2, 2014. At least 38 people were killed in a fire on Friday in the trade union building in the center of Ukraine's southern port city of Odessa, regional police said. [Photo/Agencies]

Ukraine?crisis

Ukrainian mayor wounded by gunfire

KIEV - At least 38 people were killed on Friday when radicals set fire on a building in Ukraine's Black Sea city of Odessa, the interior ministry said.

It said 30 people died of carbon oxide intoxication, while eight others died from jumping out of windows of the building of regional council of trade unions.

Up to 50 people, including 10 policemen, have sought medical assistance due to the blaze, which Kiev blamed on the Right Sector, a Ukrainian ultra-nationalist group, and self-defense militants.

Local police told Russia's Itar-Tass news agency that riots emerged earlier in the day between football fans from the eastern city of Kharkov and Right Sector radicals who had come from Kiev.

The clashes came the same day as Ukraine initiated a military assault in its eastern city of Sloviansk in a bid to retake government buildings occupied by pro-Russia activists.

Ukraine's Defense Ministry has confirmed the loss of two helicopters. It said the aircraft were shot down by a surface-to- air missile, which proved the activists were not civilians but well-equipped and well-trained militants.

The Kremlin said the assault meant Kiev had "crossed out" the Geneva agreements reached on April 17.

Calling the military move a "manifestation of a crime of feebleness of Kiev authorities," Russian Prime Minister Dmitry Medvedev urged those in power to "come to their sense ... otherwise the country's fate might be completely sad."