Odessa police call for calm after 42 people die in protest clash

This image made from AP video shows a building on fire in Odessa, Ukraine, on Friday, May 2, 2014. Deadly clashes took place in the southern Ukraine port of Odessa on Friday, triggered by Ukraine's offensive to recapture the eastern city of Slovyansk from pro-Russia forces. (AP Photo via AP Video) (The Associated Press)

Ukrainian Army soldiers are seen atop of a bridge while Pro Russia civilians block the road in the village of Andreevka, 10 km south of Slavyansk ,Ukraine, Friday, May 2, 2014. Russia has massed tens of thousands of troops in areas near Ukraine’s border. Kiev officials claim Russia is preparing to invade and that it is fomenting the unrest in the east, where insurgents have seized government buildings in about a dozen cities in towns. Moscow denies the allegations, but Foreign Minister Sergey Lavrov has warned Russia would respond to attacks on Russian citizens or interests in the east. (AP Photo / Manu Brabo) (The Associated Press)

A Pro Russian woman and an Ukrainian Army commander take cover from the rain while Pro Russia civilians block the road in the village of Andreevka, 10 km south of Slavyansk , Ukraine, Friday, May 2, 2014. Russia has massed tens of thousands of troops in areas near Ukraine’s border. Kiev officials claim Russia is preparing to invade and that it is fomenting the unrest in the east, where insurgents have seized government buildings in about a dozen cities in towns. Moscow denies the allegations, but Foreign Minister Sergey Lavrov has warned Russia would respond to attacks on Russian citizens or interests in the east. (AP Photo/Manu Brabo) (The Associated Press)

The police chief in Odessa is calling on residents of the Ukrainian port city to remain calm in the wake of violence between government supporters and opponents that left at least 42 people dead.

The deaths came Friday in a clash that started with street fighting then turned into a conflagration when government opponents took shelter in a building that then caught on fire, reportedly because of firebombs thrown through the windows.

The local office of the emergencies ministry said Saturday that 36 bodies were discovered inside the building. Before the fire, police said at least three people were killed by gunfire. The Interior Ministry on Saturday said the total casualty toll was 42, but did not give a breakdown.