A 30-meter stretch of highway along a viaduct near the flooded coastal city of Savona collapsed, leaving cars suspended on a precipice.
A driver of one of the cars closest to the edge where the bridge gave way stood outside his vehicle, holding up his arms towards oncoming traffic to warn others.
Meanwhile, around 150 people were evacuated from homes in the region, while the neighborhood of Boccadasse, in Genoa, was flooded after the sea rushed over retaining walls and onto the road.
Elsewhere in northern Italy, a woman was found dead after floodwaters swept away her car. In Turin, the Po burst its banks and flooded the medieval quarter and a popular riverside strolling area known as the Murazzi.
Meanwhile, in the south, cars drove through water higher than their tires, and several drivers had to be rescued from their vehicles in Reggio Calabria.