Updated 12:40pm

At least 13 people have died after flash flooding hit parts of south-west France overnight.

Around 180mm of rain fell on the region of Aude, with officials warning that the level of one river was likely to rise by six metres over the course of several hours.

Some areas have been evacuated, while all schools and colleges in the area have been closed for Monday.

Residents in some areas of the city Carcassonne were urged to 'go upstairs' in their homes as floodwaters increased.

A local official said that some people were trapped on rooftops, and helicopters were being deployed to rescue some people.

Rescue workers, background, secure the area by a collapsed bridge in the town of Villegailhenc, southern France. Picture by: Fred Lancelot/AP/Press Association Images

French media reports that one of those who died was a nun who was swept away by water.

According to BFM TV, one person was injured when a house collapsed in Cuxac.

On Monday morning, authorities told locals to remain alert - warning that river levels could still 'increase rapidly'.

Around 700 firefighters have been deployed, while French Prime Minister Édouard Philippe is set to visit the affected area today.