Paris, France (CNN) -- A winter storm named "Xynthia" battered the western coast of Europe Sunday, its high winds downing trees and power lines and leaving as many as 55 people dead, authorities said.
Hardest hit was France, where at least 45 people were killed, French Prime Minister Francois Fillon announced.
The extra-tropical cyclone whipped the country's coastal regions and moved inland, bringing sometimes heavy flooding with it.
"It's a national catastrophe," Fillon said in a brief news conference following an emergency meeting on the situation. "Many people drowned, surprised by the rapid rise of the water.
"Now the priority is to bring all the people left homeless and still threatened by the rising waters to safety," the prime minister explained. "All services are mobilized to reach that goal as soon as possible."
French President Nicolas Sarkozy will visit the department of Charente-Maritime Monday, Fillon said. Charente-Maritime and Vendee, on the French coast west of Paris, had severe flooding when the strong winds whipped up the water at high tide.
"At 3 o'clock in the morning, we heard the toilets backing up. We got up to look and then we saw 80 cm (about 31 inches) of water in the garage," a resident of Aiguillon-Sur-Mer, in the department of Vendee, told CNN affiliate BFM-TV.
"It was rushing in, it broke down the walls around the garden and the gate."
Hundreds of people had to be rescued from their rooftops overnight.
"The water was up to the gutters," said one woman, who spent the night on the roof with her children. Residents of the village of Aytre, in Charente-Maritime, saw a wave of water measuring 1 meter high (about 1 yard) come into the center of town.
One couple told BFM-TV their children were airlifted and they were taken out by boat. "It rose very high, very high, we were very scared," another man told the station. "It was unreal," Aytre Mayor Suzanne Tallard told BFM-TV.
At least 1 million households were without power Sunday afternoon, Bernard Lassus of Electricite de France said in an interview on BFM-TV.
French Interior Minister Brice Hortefeux told BFM-TV that 350 soldiers and 3,250 firefighters have been mobilized. About 10 helicopters are being used to airlift people, he said, and draining operations were underway.
The high winds -- at times spiking to 200 km/h (124 mph) -- reached inland as far as Paris, where as many as 100 flights were canceled at the Paris-Charles de Gaulle International Airport, BFM reported.
Gusts up to 175 km/h (108 mph) were measured at the top of the Eiffel Tower Saturday, reported CNN International Meteorologist Eboni Deon.
The hurricane-strength winds stretched from Portugal northeast to the Netherlands. The system was moving toward the Baltic Sea, Deon said, and a second front was moving into the region of Portugal and Spain later in the day.
In Spain, three people were killed in the first band of the storm, Spanish Interior Minister Alfredo Perez Rubalcaba said Sunday. Two children died in a car accident and another person was killed in northwestern Spain, the minister said in a news conference on CNN sister station CNN+.
At least 17 provinces were on high alert due to the strong winds, CNN+ reported, and some flights and train services were canceled.
A 10-year-old child was killed by a falling tree in the high winds in Portugal, Patricia Gaspar, National Operations Assistant with the Portuguese National Authority for Civil Protection, confirmed to CNN. There are also some power outages in the country, Gaspar said.
Some residents have reported roofs blown off and smaller houses collapsing, she added.
Four people were killed in Germany as a result of the storm, officials said -- all four when they or their cars were struck by falling trees. One of them, a 69-year-old man, was a hiker in a group of about 20, police said, but the others were evacuated to safety.
A man was also killed by a falling tree in Belgium, Peter Mertens, a spokesman for Belgium's Interior Ministry, confirmed to CNN. Eastern Belgium has seen the worst of the storm, Mertens said. "They've had problems with fallen trees, roofs blown off and electricity cables not working. But it seems the worst part has passed now," he added.
The storm also reached England, where one woman was reported dead when the vehicle she was driving became submerged and washed down a swollen creek in the northeastern part of the country. The body of the 53-year-old woman was recovered downstream, North Yorkshire Police said in a recorded phone message to the media.
CNN's Al Goodman in Madrid, Spain; Per Nyberg in London, England; Frederik Pleitgen in Berlin, Germany; and Estelle Eonnet and Lorraine Gublin in Paris, France contributed to this report