Sloviansk, the headquarters of the pro-Russia separatists controlling large pockets of eastern Ukraine, looked to be on the cusp of descending into brutal street warfare today.

This morning, fierce fighting erupted on the northern outskirts of the city as Ukraine Special Forces inched their way forward into a civilian zone and engaged in more than an hour of heavy gunfire exchange with the pro-Russia separatists.

"They just started shooting at us, at house, shops," Valera, a local farm worker told VICE News, pointing at the bullet holes in local houses fences and garage doors.

"Look at the damage, look at what they have done to where we live, it is destroyed," Valera said.

Church bells and sirens reportedly sounded as the attack began.

“We were given no warning, no time to get out, my 7-year-old son was terrified," distraught local and mother Irina told VICE News.

Following more than an hour of gunfire exchange this morning, four Ukrainian soldiers were reportedly killed in the clashes. According to pro-Russia separatists, at least 20 fighters were killed on their side.

The Defense Ministry said that one of their helicopters was gunned down during this morning's assault — the third chopper to be shot down by separatists in just three days.

Tensions were high in Sloviansk on May 5, amid reports of a government offensive against pro-Russian separatists.

Speaking by telephone to VICE News, Roman, an officer in a SBU unit deployed in the region, said he had been transferred to Kramatorsk for treatment of two gunshot wounds in his leg.

The death toll has been hard to confirm in the chaotic environment, but high numbers of civilian casualties are further fueling anger among the local population.

Today, the funeral for 21-year-old nurse Yulia Izotova was held. She was killed on the outskirts of her hometown, Kramatorsk during clashes between the Ukrainian army and separatists.

The Kiev-backed counter-terror operation, now in its third active day, is the first serious attempt to oust the pro-Russia separatists from their stronghold in the east.

Clashes in Pro-Russia Controlled Separatists Regions

Sloviansk, as well as Luhansk, Kramatorsk and Horlivka, have been under the armed pro-Russia milita group operation in the area for more than two weeks.

Over the last week, the Ukrainian army has slowly advanced their positions forward, moving ever closer to the city center and the separatists.

Tensions were high in the town of Sloviansk on May 5 amid reports of a government offensive against pro-Russian separatists.

Local support for the pro-Russia militia is strong and many in Sloviansk and surrounding villages see the Ukrainian army as an invading rather than liberating force.

The blurred line between the unarmed locals who support the separatists and those who actively participate in the armed militia force presents a serious challenge for the Ukrainian forces who are already facing a hostile local population.

Two previous attempts to dislodge the rebels were abandoned.

On one occasion, an angry mob of villagers managed to turn back a convoy of Ukrainian soldiers and armored personnel attempting to secure a local airport.

And a few days ago as Kiev-backed forces first pushed forward, villagers placed trees along all the major routes into the separatist-controlled city, creating a gauntlet of trunks to prevent military vehicles passing.

The vehement pro-Russia sentiment in the region means that fighting is likely to descend into guerrilla style street warfare as troops push forward into civilian areas — making even harder for the army to distinguish between peaceful citizens and the militia, who may seek shelter or make bases inside sympathetic locals' houses.

The presence of several hundred newly deployed special police officers spotted by VICE News arriving just behind the army line on this afternoon suggests the operation may be preparing to move into a door-to-door stage to push out the separatists, if so, the potential for loss of innocent lives becomes even higher.

Violence in Odessa has also fueled fears that the east and southeast regions of Ukraine may descend into civil war.

On May 3, more than 30 pro-Russia activists were either asphyxiated or leaped to their deaths after being trapped in a building during clashes with pro-Ukrainian protesters.

The deadly event is already being labeled a genocide. Police have been accused of having failed to act to prevent the violence.

Today, the funeral of an Odessa government official who died in the blaze, Vyacheslav Markin, attracted hundreds of mourners.

"Glory to the Odessa heroes" and "never forget, never forgive" chanted the crowd as the coffin was carried past.

On Sunday, angry protests in the port city, by both sides, continued throughout the day and into the night in the port city, with some demonstrators arming themselves with chains, bats and Molotov cocktails.