Ukrainian officials said the attack was deliberate. When dropped from planes on the Russian side of the front line, such bombs can glide to fixed coordinates on the ground. In this case, the target was a street in Kramatorsk, about 20 kilometres (12.4 miles) from the front line.
"The Russians are deliberately targeting civilians," regional administration head Vadym Filashkin wrote on Telegram. "For them, a bus full of passengers is an attractive target precisely because a single strike can kill the maximum number of people." Filashkin added that Russia "consciously disregards all conceivable rules of warfare and norms of international humanitarian law. It selects targets where it can inflict the greatest suffering on civilians."
Filashkin ordered the suspension of all public transportation in Kramatorsk and neighbouring Sloviansk as Russia intensifies attacks, paralysing Ukraine's transport infrastructure, from trains and minibuses to gas stations, bridges, seaports and freight ships.
"This is a new Russian tactic," Volodymyr Fesenko, head of the Kyiv-based Penta think tank, told Al Jazeera. "They used to focus on depriving Ukraine of power, on switching off electricity and heating; now their task is also to immobilise the infrastructure, create a transportation collapse."
Fesenko said the tactic has a certain effect with strikes on railroads and gas stations. "They coerce to peace on their conditions," he said. "They also strike the public psychologically, disrupt the usual lifestyle in general."
Throughout the war, Russia has denied it targets Ukrainian civilians.