A Russian drone strike on Sumy in northeastern Ukraine has killed three family members, including a 13-year-old boy. Officials also said Monday that a Ukrainian strike on a Russian industrial plant killed five people. Russia has targeted Ukrainian civilian areas with drones and missiles since its invasion over four years ago. Ukraine has increasingly struck back at Russian oil facilities and military factories. A United Nations tally says more than 16,000 civilians have died in the war. U.S.-led peace efforts have failed to stop the fighting. Ukraine's monthly civilian casualties are the highest in four years.