Ukrainian drone strikes killed at least two people in regions along Russia's Volga River overnight, hitting targets including a warehouse belonging to Wildberries, Russia's largest online retailer, regional officials said on Sunday.

Russia's Defense Ministry said it had downed 635 Ukrainian drones overnight.

Kyiv's drones attacked a Wildberries warehouse in the Samara region, around 800 kilometers (500 miles) from Ukraine's most advanced military positions inside Ukrainian territory it holds, regional Governor Vyacheslav Fedorishchev said. He added that information on potential casualties was still being clarified.

Ukrainian forces have been striking deeper inside Russia as they ramp up strikes on economic and energy targets, hoping to undermine Moscow's ability to wage its more than four-year war in Ukraine.

They have attacked about a dozen Wildberries sites since July 18 in a bid to disrupt the operations of the company, a linchpin of the consumer economy often described as Russia's answer to Amazon.