Ukraine on Thursday observed a day of mourning after 32 miners perished in a blast in a notoriously dangerous mine just a few kilometers from the frontline, where Kiev is reporting an increase in attacks by pro-Russian separatists. Rescuers found the bodies of 32 miners in the Zasyadko mine, with one person unaccounted for, a day after a blast ripped through the shaft, emergency officials of the self-proclaimed Donetsk People's Republic said. Nearly half the bodies had been brought to the surface, according to the pro-Kiev administration of the Donetsk region. "The rescue operation is still ongoing so the figure may change," it said. Survivors were meanwhile being treated in hospital for burns and gas poisoning. The Zasyadko mine is located on the outskirts of rebel hub Donetsk not far from the frontline of the conflict between the pro-Russian separatists and Kiev's forces. International monitors have reported sporadic heavy fire in the area of the Donetsk airport nearby despite the EU-mediated ceasefire struck on February 12. A Ukrainian military spokesman Vladislav Seleznyov said one soldier was killed on the frontline over the past day, the sixth Ukrainian casualty since Sunday. Donetsk region prosecutors have launched a probe into the possible violation of safety precautions at the mine, but conceded that an investigation would be impossible as the mine, though it is registered in Ukraine, is de-facto under control of pro-Russian separatists. Rebel prosecutors said they had launched a probe of their own. Ukrainian President Petro Poroshenko late Wednesday decreed a nationwide day of mourning Thursday, ordering that the Ukrainian flag be flown at half-mast and cancelling entertainment events. The parliament at midday observed a minute's silence. Both Ukraine and Russia have offered to help with the search for survivors but the separatist authorities claimed that they had enough people and equipment. Access to the mine was closed off by the rebels Thursday morning, and psychologists at the scene were trying to comfort two women convinced that their miner husbands have died.