Aug 2 (Reuters) - Ukrainian drone strikes killed at least eight people in Russian regions overnight and on Sunday, hitting targets including a warehouse belonging to Wildberries, Russia's largest online retailer, regional officials said. The acting governor of Russia's border region of ‌Belgorod, Alexander Shuvayev, said a Ukrainian drone struck an area next to a playground, killing one child and injuring two. Ukraine's drones attacked a Wildberries warehouse in the Samara region, around 800 km (500 miles) from Ukraine's most advanced military positions, Samara Governor Vyacheslav Fedorishchev said. A strike on a residential building ​in ​the neighbouring Saratov region killed two people in the city of ​Engels, Governor Roman Busargin said. Ukraine's military said on Sunday that Ukrainian forces attacked the Saratov refinery and the Engels airbase, sparking fires at both facilities.