The storm shut roads, halted trains and cut power to areas in France, Italy and Switzerland.

Although snow in April is not rare in the Alps mountain range, the amount that fell in just hours was unusual and took authorities and residents by surprise.

It Italy, the bodies of a 64-year-old man and his 33-year-old son were found near Vicenza in the Venetian region, bringing the death toll in the country to three.

The pair had volunteered to help with rescue efforts after heavy rains lashed the north of the country and were on their way when their car was swept away by the currents unleashed by the deluge in what the head of the region, Luca Zaia, called an "unimaginable tragedy."

The previous day, a 92-year-old man was found dead in his flooded home in the northern Piedmont region, the fire brigade said.

"Intense and abundant" rain had drenched the north of Italy, turning to snow above 1,800 metres (5,905 feet) altitude, an official said.

In the French resort of Val Thorens, a 27-year-old British man had a heart attack after being buried by an avalanche, and died, authorities said.

And in Tignes, authorities ordered residents to stay indoors after more than 1.1 metres (three and a half feet) of snow fell overnight.

"All cars are covered up to the roof... Just walking outside is worrying," said Mathis, a hotel employee in Tignes.

Avalanche risk was hiked to its maximum level in several regions, shutting down several ski areas.

The 36,000 people in the Swiss town of Sion were also told to stay home.

"In such a short time, this is an enormous amount (of snow)," said Yann Geaudry, a retired cross-country ski instructor in the French village of Termignon, who was worried about the risk of floods when the snow melts in the spring sunshine.

Many roads were shut in all three countries due to fallen trees or the risk of avalanches.

Heavy trucks were banned from using the main Mont Blanc tunnel between France and Italy and dozens that could not get through tunnels were stuck on the A43 highway linking Italy and France.

Trains were also affected, and at one point more than 3,300 homes in France and 5,000 households in Italy were left without power, according to authorities.

"It's truly exceptional," said Didier Beauchet, a retiree who has lived in Lanslebourg in Savoie for 40 years.

"I must have seen that only five times," he told AFP, as motorists around him worked to free their snow-covered cars.

burs-yad/giv