Flash floods in southwest France have left at least 13 people dead, according to local authorities cited Monday by the Associated Press. Overnight storms caused the worst flooding of the river Aude in over a century, the Associated Press reports. BBC News notes that in some regions, floodwaters rose more than 23 feet, and that one of the 13 victims is a nun who was swept away by the raging waters. In Trebes, the hardest-hit city, nine people were killed. In Villegailhenc, a witness told the Associated Press, the waters rose so quickly that residents were stranded on their roofs and required rescue from a helicopter. A video she posted on Twitter shows a road demolished by murky brown floodwaters where a bridge previously stood. “There’s nothing left. There’s just a hole,” she said. “It was very violent.” BBC adds that more than 700 emergency service workers and seven helicopters have been dispatched for rescue efforts, and that Prime Minister Édouard Philippe plans to visit the region if conditions become safer.