Three open coffins, one adult-sized, one medium and one child-sized, lay inside the Soviet-era Palace of Culture in a northern Ukrainian city. They were surrounded by dozens of bouquets Wednesday as a church choir sang farewell prayers, and hundreds of residents stood in grim silence. The siblings, aged 8, 12 and 17, were killed over the weekend when debris from a Russian cruise missile slammed into their home in Korostyshiv, about 100 kilometers (60 miles) west of Kyiv, during an aerial barrage. The attack came at 3 a.m. as they slept in their beds. The children’s deaths underscore the mounting toll on Ukrainian families as Moscow ramps up its strikes amid faltering peace efforts.