Clashes between the Ukrainian military and pro-Russian militants in Eastern Ukraine broke out on Monday according to CNN.
The Ukrainian military is attempting to expel pro-Russian gunmen from the eastern town of Slovyansk.
At least four people have died and 30 were injured in the most recent violence in the area.
According to CNN:
[Ukraine's Interior Ministry] quoted local residents as saying the attackers had shot at residential buildings and set them on fire. Militants blamed Ukrainian forces for the civilian casualties.
In a separate statement, the Ukrainian Defense Ministry said a military helicopter was shot down "during a combat mission and patrolling in the area" of Slovyansk on Monday, but the pilots survived after it crashed into a river. They were later rescued.
Ukraine's embattled new leaders have launched their most intensive effort yet to dislodge pro-Russian separatists who have reportedly seized government buildings in nearly a dozen cities and towns.
Kiev authorities describe the separatists as "terrorists." But the rebels say they are defending Russian-speaking areas of the east against Ukrainian "fascists" trying to root out Russian influence in the country.