Central Europe began counting the cost of deadly and devastating floods caused by Storm Boris, as the European Union pledged billions of euro in aid to affected countries and northern Italy became the latest area to be inundated by torrential rain.

A massive flood wave moving across Central Europe threatened new areas after claiming 24 lives, raising concerns among residents and officials and prompting European Union chief Ursula von der Leyen to plan a visit to the region Thursday.

The north-east and central regions of Italy are being battered, days after the storm caused widespread flooding in central Europe.