At least four people died overnight as Russian drone and missile strikes continued to pound Ukraine’s towns and cities, local officials said Saturday. Meanwhile, Moscow’s troops continued their grinding advance through the country’s east.

Russia launched a barrage of drones and missiles on Ukraine on Saturday, killing at least four civilians and damaging residential buildings and infrastructure across the country, Ukrainian officials said.

Russia’s ability to keep making fuel at the normal pace is looking increasingly precarious following a surge in Ukrainian drone attacks on the nation’s oil refineries, including a fresh incident on Friday.