Four people – including three children – were killed in separate Russian attacks in Ukraine’s southern Mykolaiv region, and another two in the north-eastern Kharkiv region, local officials said.In the southern city of Zaporizhzhia, three people were injured when a drone exploded near a taxi, the regional head said.This comes a day after 17 people were killed and more than 40 injured in a major Russian missile and drone attack on Ukraine’s capital Kyiv.Blocks of flats and warehouses were struck overnight across the city, local officials said. A children’s hospital and school were also damaged.Earlier on Friday, Ukraine’s military said it carried out strikes on an oil refinery and a military airfield deep inside Russia.Ukraine has in recent months intensified attacks on Russian energy facilities, as well as on warehouses of the country’s largest online retailer Wildberries. Kyiv describes them as legitimate targets because they help finance Russia’s war.Russian President Vladimir Putin launched a full-scale invasion of Ukraine in February 2022, and currently Moscow controls about a fifth of Ukrainian territory in the south-east.