At least 10 people have died and 13 have been injured today after a passenger bus was shelled in the town of Volnovakha, about 22 miles southwest of the rebel stronghold Donetsk, according to Ukrainian authorities. There was also heavy fighting at Donetsk airport, where fire from separatist tanks reportedly destroyed the airport's control tower.
The Donetsk regional administration, which is accountable to the government in Kiev, claimed that the pro-Russia forces of the Donetsk People's Republic (DPR) hit the bus while it passed through an army checkpoint near Volnovakha.
The head of Donetsk regional interior ministry, Vyacheslav Abroskin has confirmed Ukrainian forces are investigating the attack. "It was a direct hit on an intercity bus. An investigation is in progress. The road between Donetsk and Mariupol has been closed," Abroskin said.
However, a DPR official told Russian news agency TASS that it denied any responsibility, claiming: "All accusations that these were the militiamen who opened fire at the bus are devoid of elementary logic. We are not idiots to fire on our own territory".
The DPR defense ministry also described the incident as "a provocation on the part of Ukraine."
These civilian deaths came in the wake of skirmishes at Donetsk airport today, where the iconic control tower was destroyed.
The Interpreter translated Ukraine's LIGA Novosti report from one of the Ukrainian soldiers defending the airport, also known as Cyborgs, who said the pro-Russia rebels besieging the tower had issued an ultimatum: "They're smashing us from both sides with tanks 400 meters away and artillery. We have no support from our artillery. The militants have given us until 17:00 to leave the new terminal."
After that deadline passed, heavy shelling was audible on the Ruptly live feed, a video news service from Russia's state-owned TV channel Russia Today.
Igor Strelkov, the military rebel leader, has since tweeted suggesting that the rebel attack was successful: "As a result of today's fighting Donetsk airport is fully under our control!"
This will come as a setback to the Ukrainian forces, who regarded the control-tower not only as a strategic stronghold, but also as a symbol of their resistance against Russian oppression.
A lack of progress in establishing another ceasefire in the region has also meant plans for a summit this week have been cancelled. Russian, French, and German leaders had been invited to attend talks on Thursday in the Kazakh capital Astana by Ukrainian President Petro Poroshenko.
But, following discussions held earlier in the week the four countries' foreign ministers have said the failure to bring about a truce completely meant that "further work needs to be done" before a summit could be held.