Three months' worth of rain fell in just a few hours overnight in a region called the Aude department, according to the ministry.
Earlier today, the ministry said the death toll was 13, but has now revised to 10. The spokesperson did not specify why the death toll has decreased since this morning.
Pictures taken this morning show a massive amount of destruction, including flooded roads, collapsed homes and overturned cars.
French Prime Minister Edouard Philippe described the emergency crews on scene via Twitter.
"350 firefighters are on the scene. 350 more firefighters are on their way. 7 helicopters have been mobilized. I am keeping myself informed of the situation hour by hour."
Philippe said he will travel to the area this afternoon.
Local authorities said in a statement that more than 1,000 people in a village called Pezens were evacuated this morning because of risks posed by a dam located a few miles away.
In addition, schools in the area remain closed and local authorities are urging people to stay home.
As of Monday morning, 8,000 homes in the region remained without electricity, according to supplier Enerdis.