"We haven't seen anything like this in a decade.
"The emergency services are concentrating for the time being on clearing up in order to rebuild minimal living conditions for the population affected by the disaster," he said.
More than 1,400 people were rescued by helicopter and about one hundred rescue missions were carried out by boat.
More than 2,000 people had been taken to shelter since Tuesday.
"This morning, we woke up to find a city that was devastated, extremely battered with overturned cars floating in the streets, collapsed roads and gutted houses," Corinne Orzechowski, the head of the emergency operation, said on Wednesday.
"We are still in the rescue phase before moving on to the cleanup."
The disaster reached the popular tourist town of Frejus where more than 1,500 people were taken to safety, many in inflatable boats or by helicopter airlift to four shelters.
About 90,000 households remained without electricity and phone lines were down for 15,000 residents.
Schools and colleges were closed on Thursday but centres were open for students taking school exams.
In February, a ferocious storm and surging tide killed 53 people in southwestern France.