Heavy rain cut the road linking the Bulgarian capital with the main border into Greece, police announced Sunday, as alerts were in place in parts of the country after flooding and falling temperatures.
The E-72 road to the Koulata-Promahon border crossing was closed and drivers wanting to enter Greece had to travel to the Ilinden-Exohi border post about 100 kilometres (60 miles) to the east, they said.
The Strouma River broke its banks overnight, flooding the road. A longhaul truck had overturned in the river but there were no victims, police said.
Seven people, including three children, had meanwhile been trapped since Saturday in a cave near the city of Pernik, just west of Sofia, after rising water blocked their access to the exit, authorities said.
Flooding had damaged about 30 houses in Pernik, where a dam was destroyed.
Alerts were in place in several western and southern areas and while the rains had stopped Sunday, authorities were concerned about black ice after a sharp fall in temperatures.
Much of Europe has been struck by an early cold snap, which 46 people dying in freezing weather in Poland since the beginning of November.