Some 340 people were evacuated overnight from stranded vehicles on roads across Romania, Prime Minister Emil Boc said, and another 100 people were transported during the day to Bucharest after getting stuck on two major roads.
Health officials said a man died and a woman was hospitalized in serious condition after they were found unconscious in a car about 11 miles south of Bucharest. A hospital spokesman said the woman was suffering from hypothermia and carbon monoxide poisoning.
About 1,300 people have been given temporary shelter since Wednesday morning, said the Interior Ministry, and forecasters are predicting that temperatures will fall as low as -16 degrees C (3F).
A train derailed on icy tracks in the country's south, but nobody was injured, and about 28 flights were canceled on Thursday, along with 49 trains, Romanian officials said.
Defense Minister Gabriel Oprea said defense ministry employees were helping to clear snow in an operation involving tanks and other military vehicles.
Authorities said 40 towns and villages in southern Romania suffered power outages. In neighboring Bulgaria more than 100 communities were left without electricity, while traffic was snarled in many areas.
Bulgaria's main Black Sea port of Varna was closed for traffic due to windstorms and heavy snowfall, port officials said. The heavy snow forced authorities to close several mountain passes as well as many schools.
Southern and central Serbia were also badly hit. Many villages were cut off due to the snowfall, and some residents had a difficult time feeding their animals. In the village of Lunjevac, in central Serbia, a villager hired a horse-drawn cart to help him reach a nearby hospital.
Authorities said a key road linking Serbia to Macedonia to the south, was blanketed with snow but still passable. Thousands were left without electricity, while railway traffic was halted in many areas.
Further west, in the Swiss resort of Davos, which is currently hosting the annual World Economic Forum, there were snowbanks some six feet high lining the streets and snow clearing machines working all over town.