ROME - A 30-meter portion of a highway viaduct collapsed after a landslide amid torrential rains in the northwestern Liguria region as adverse weather lashed the Italian peninsula causing swollen rivers and extensive flooding on Sunday.

In a separate incident also on Sunday, one person died in a car that was swept into a river by floodwaters in the northern Piedmont region.

"Landslide on A6 highway viaduct, firefighters searching for possible vehicles involved," the Fire Department tweeted, along with aerial video footage of the collapsed infrastructure in the Liguria region, whose capital Genoa suffered a disastrous viaduct collapse in which 43 people died in August 2018.

"We cannot confirm nor deny that there were cars passing at the time of the collapse," Liguria regional authorities tweeted. "A rescue helicopter is searching the area."

Also in the Liguria region over 100 people were evacuated from their homes and a total of 800 people are isolated due to landslides caused by torrential rains, regional authorities said on Twitter.

Some 50 landslides occurred across Liguria, which will request a state of emergency from the government, authorities said on Twitter.

In the northern Piedmont region, near the city of Alessandria, a woman went missing after a car with three people on board ended up in the Bormida river. Firefighters rescued two people and the search for the third occupant of the car lasted into the late afternoon, the Fire Department said on Twitter.

"The body of the woman who went missing this morning in the waters of the Bormida river has been found," the Fire Department tweeted.

In the same area around the city of Alessandria, another 200 people were evacuated and hundreds of homes were left without power after two smaller rivers broke their banks and flooded surrounding villages and towns.

In Turin, which is the capital of the Piedmont region, the Po river has flooded parts of the city and authorities have canceled the city marathon supposed to take place on Sunday morning. Twenty-three roads have been shut down due to floods and landslides, city authorities said on Twitter.

In the northern Lombardy region whose capital is Milan, the Lugano Lake, part of which lies in Italy and part in Switzerland, has risen and flooded villages on both its Italian and its Swiss coasts, the Fire Department reported on Twitter.

The Po river, which runs across northern Italy, has risen by three meters in the past 24 hours, Italian farmers' association Coldiretti said in a statement on Sunday, noting that this has caused floods "from Liguria and Piedmont to the Emilia Romagna and Veneto regions".

"Destroyed vegetables, lost animal fodder, devastated vineyards and fruit groves, unusable greenhouses, damage to buildings and farming equipment submerged in mud are the results of the latest wave of adverse weather, which has brought damages to over 100 million euros" in the Po River basin stretching across northern Italy, the Coldiretti statement said.

The civil protection agency has issued weather alerts across most of Italy for Monday, saying it expects strong winds, torrential rain and lightning. (1 euro = 1.10 U.S. dollars)