There have been casualties in Slovyansk after clashes between separatists and government forces. Local residents talked of heavy gunfire resounding across the city on Monday morning.

Ukraine’s Interior Ministry confirmed four Ukrainian soldiers were killed and 30 injured.

Local media sources say 15 of the rebels have been injured; it’s understood there have been fatalities though that has not been clarified.

A barrier was erected near a local hospital where the injured rebels were treated. Some of the victims, it’s reported, came from the local population.

The crew of a Ukrainian military helicopter survived after it was shot down and crashed into a river the Interior Ministry said in a statement. It is the third to be downed in the area in the space of four days.

It’s estimated that around 800 pro-Russian militants were involved in the clashes.

Government forces took control of a TV tower and rebels retreated deeper into the city, according to the Russian agency Interfax.

Moscow warned Kyiv on Monday that a humanitarian crisis was looming in blockaded towns in the east, and called on the government to stop using force against its people.

It said Kyiv should, “withdraw forces and sit down at the negotiating table to begin a normal dialogue about ways to resolve the political crisis.”