Separately, an explosion on the Trans-Siberian pipeline occurred in central Ukraine on Tuesday, in what some are calling an act of terror.
The attack marks the biggest losses to Ukrainian forces from a single event since the conflict in Ukraine’s east began.
Vyacheslav Ponomaryov's absence, reportedly since Monday, is "shocking the DPR," a representative said today.
Residents are fleeing from ongoing fighting and shortages in the east of Ukraine, as new president Petro Poroshenko discusses peace.
Surrounded on all sides by the Ukrainian army, civilians trapped inside Sloviansk are subject to daily shelling from mortars and artillery.
The DPR's move for the airport crossed a line and this time the Ukrainian army stood up to rebels and retaliated with merciless force.
With less than a week to go, armed pro-Russian rebels are upping the ante with a campaign of violence to stop the vote in Kiev.
Around a dozen militia fighters have been killed in the Kiev-backed sting in a series of assaults on the rebel controlled checkpoints.
Sloviansk, as well as Luhansk, Kramatorsk and Horlivka, have been under the armed pro-Russia milita in the area for more than two weeks.
The anti-terror operation announced by Kiev earlier this week is the third attempt to oust the pro-Russia forces controlling large regions.
Seven members of the Organization for Security and Cooperation in Europe (OSCE) were freed after being detained last week.