Russia unleashed a new wave of major attacks on Ukraine on Saturday, hitting energy infrastructure across the country and killing at least 14 people in a missile strike on a nine-story apartment building in the city of Dnipro, officials said.

Rescue teams toiled through the night in freezing temperatures in the aftermath of the Dnipro attack, in east-central Ukraine, with local officials saying people were still alive underneath the massive pile of wreckage. "They keep sending SMS-es," Mikhailo Lysenko, deputy mayor of Dnipro said in a social media video. "We stop our work now and then to keep silence and we hear people scream from underneath the rubble."

Russian strikes also hit critical infrastructure in Kyiv and other places, with Ukraine's energy minister saying the coming days would be "difficult" with threats to the supply of electricity, running water and central heating at the height of winter.