Three emergency workers were killed in a helicopter crash near Marseille while on a rescue mission in southern France where floods left at least another three dead, officials said Monday.

Their EC145 helicopter lost radio and radar contact while on a rescue and reconnaissance flight in the Var region Sunday night.

The French Riviera has been hit by torrential rains
The French Riviera has been hit by torrential rains AFP / Yann COATSALIOU

The three swept away by floodwaters were found dead at 1:30 am near the town of Rove, Interior Minister Christophe Castaner and his secretary of state Laurent Nunez said in a statement.

An investigation was under way to determine the circumstances of the crash after the copter smashed into a hillside at Pennes-Mirabeau, a small hamlet to the north of Marseille.

The French Riviera has been hit by torrential rains
The French Riviera has been hit by torrential rains AFP / Yann COATSALIOU

"While France is preparing today to pay tribute to 13 of its soldiers who died serving it (in Mali), our country is losing three everyday heroes who gave their lives to protect the French," Castaner and Nunez said in a joint statement.

President Emmanuel Macron tweeted that even though Sunday's red alert for the area had since been lifted the atrocious weather "leaves behind it lands devastated and plunged into mourning by the flooding."

The Var and the neighbouring Alpes-Maritimes region were on red alert for floods, which disrupted train services and closed a motorway for four hours Sunday evening
The Var and the neighbouring Alpes-Maritimes region were on red alert for floods, which disrupted train services and closed a motorway for four hours Sunday evening AFP / Valery HACHE

He added that his thoughts were with all those affected, "particularly with the families and loved ones of those of our fellow citizens who have lost their lives."

Three people were killed on Sunday by the floods in the French Riviera, which was lashed by fresh torrential rains a week after extreme weather left six dead in the Var region.

In the same region, a shepherd was swept away as he was trying to cross a ford in his 4x4 while tending to his flock. His body was found in his vehicle late Sunday 300 metres (yards) downstream from where he was last seen, the prefecture said early Monday.

Interior Minister Christophe Castaner confers with local prefect Pierre Dartout as he is briefed on the helicopter accident and the flooding
Interior Minister Christophe Castaner confers with local prefect Pierre Dartout as he is briefed on the helicopter accident and the flooding AFP / CLEMENT MAHOUDEAU

"We urged him several times to come back, but off he went anyway," his partner told all-news broadcaster BFMTV.

Elsewhere in the same region, the owner of a stables was found dead two hours after he was also washed away while out watching over his animals, it said, while a woman was found dead in her car.

There were fears the death toll would rise with a 61-year-old woman listed as missing, also in the Var, after her car was found after the swollen waters of the River Garde receded to reveal a vehicle with its doors open but no sign of her.

Monday afternoon saw a spectacular landslide at Mees, a small village in the Alpes-de-Haute-Provence department around 100 kilometres (60 miles) north of Marseille.

Rocks destroyed several houses and injured two people, the local prefecture said, citing the "highly unfavourable weather conditions of these past few days" which it said had rendered some of the terrain above the village unstable.

The Var and the neighbouring Alpes-Maritimes region had been placed on weekend red alert for floods which disrupted train services and cut the A8 motorway for four hours Sunday evening.

Many cultural and sporting events were also called off because of the bad weather, including Paris Saint-Germain's Ligue 1 match at Monaco.