The death toll from a weekend Russian missile strike on an apartment building in the southeastern Ukrainian city of Dnipro has risen to 37, authorities said Monday, as western analysts identified signs the Kremlin was preparing for a drawn-out war in Ukraine after almost 11 months of fighting.

The victims from Saturday’s strike on the multi-story residential tower included two children, Ukraine’s National Police reported, and 15 children are among the 75 injured. The rescue and search operation was ongoing, with 39 people, including six children, taken from the ruins so far, the police said in a statement.

About 1,700 people lived in the apartment building. Residents said there were no military facilities at the site. The reported death toll made it the deadliest single attack on civilians since before the summer, according to The Associated Press-Frontline War Crimes Watch project.

The European Union’s foreign policy chief, Josep Borrell, called the strike, and others like it, “inhumane aggression” because it directly targeted civilians. “There will be no impunity for these crimes,” he said in a tweet Sunday.

Asked about the strike Monday, Kremlin spokesman Dmitry Peskov said the Russian military doesn’t target residential buildings and suggested the Dnipro building was hit as a result of Ukrainian air defense actions. The Ukrainian military said Sunday that it did not have the means to intercept the type of Russian missile used in Saturday’s strike.