SLOVYANSK, Ukraine (AP) -- The crisis in Ukraine has escalated today as the country's interim government launched its first major offensive against pro-Russia insurgents who have seized government buildings in at least 10 eastern cities.
Ukraine says many militants have been killed or wounded, while the insurgents shot down two Ukrainian helicopters.
And police say more than 30 people are dead in the city of Odessa after a building fire broke out during a clash between pro-Russia demonstrators and supporters of the central government in Kiev. The port city on the Black Sea is more than 300 miles from the turmoil in the east and until now had been mostly peaceful.
By nightfall, Ukrainian troops and armored personnel carriers had blocked all major roads into the eastern city of Slovyansk (SLAHV'-yansk), the center of the insurgency.
A spokesman for Russian President Vladimir Putin says the Ukrainian offensive has "effectively destroyed the last hope" for an agreement reached two weeks ago that aimed to defuse the crisis.
Ukraine accuses Russia of backing the insurgents. It fears Moscow is seeking a pretext to invade or annex more territory as it did with Ukraine's Black Sea peninsula of Crimea in March.