The torrent of mud engulfed five cars parked near a mountain lodge above the town, killing three people who were in the area, which is a popular ski resort during winter months.
Rescue workers found the body of a young Polish man, who was hit by the landslide after getting out of his car, La Repubblica reported.
His wife, who had remained inside, was rescued unharmed from the car's wreckage, albeit suffering from hypothermia.
The bodies of two other people, who have not yet been identified, were also found.
A team of volunteers, firemen and mountain rescue experts are now working to find any more victims who might have been caught in the landslide as it made its way down the slopes of Monte Antelao.
The wave of mud destroyed a bridge on a local cycle path and blocked the main roads into Cortina d'Ampezzo, cutting the alpine city off from surrounding villages for hours.
In the town of San Vito di Cadore, the excess precipitation caused the river to burst its banks and flooded local offices and the premises of an estate agency.
The landslide is the second extreme weather phenomenon to hit the region of Venice recently. Last month, a tornado killed one as it swept through the town of Dolo.