Massive blizzards that paralyzed much of the U.S. East Coast in the past few days are likely to cause "multibillion" dollar economic losses in one of the worst storms in the region in over a century, reinsurance broker Aon Benfield said on Monday.

The monster weather system unofficially dubbed Winter Storm Jonas left at least 20 dead in several states, with most of the fatalities the result of traffic accidents.

"Given the physical damage to homes, businesses and other structures and automobiles, plus the high costs incurred due to business interruption, it is expected that this will end up being a multibillion-dollar economic cost," Aon Benfield said in a note.

The storm would likely be rated as one of the top 15 winter storms in the Northeast and Mid-Atlantic since 1900, it added.

It was too soon to calculate insured losses, Aon Benfield said, adding a similar storm system in January 1996 caused an estimated economic loss of $4.6 billion and insured loss of $920 million in current dollar terms.

HISTORIC STORM

The blizzard was the second-biggest snowstorm in New York City history, with 26.8 inches (68 cm) measured in Central Park by midnight on Saturday, just shy of the record 26.9 inches (68.3 cm) set in 2006, the National Weather Service said.

At least 13 people were killed in weather-related car crashes in Arkansas, North Carolina, Kentucky, Ohio, Tennessee and Virginia on Saturday. One person died in Maryland and three in New York while shoveling snow. Two died of hypothermia in Virginia, and one from carbon monoxide poisoning in Pennsylvania, officials said.

A spokeswoman for the New York Stock Exchange said the market planned to open as usual on Monday. City schools also were set to open on Monday.