A man who had been mowing his lawn and sought refuge in his truck was killed when a tree fell on the vehicle in Danbury, Connecticut, said Danbury Mayor Mark Boughton, according to the Hartford Courant newspaper.
By daybreak, more than 370,000 residents were without power in New York, New Jersey, Connecticut and Pennsylvania, down from more than 600,000 on Tuesday night.
The Brookfield Police Department said on its Facebook page that First Selectman Steve Dunn had "declared a town disaster".
Downed trees and utility poles impacted MA as well, though the severity did not reach the level reported in other northeast regions.
Airlines canceled and delayed flights in and out of the region.
At Grand Central Station in NY, line service for Hudson, Harlem, and New Haven were suspended due to the storms, the station's Twitter feed said.More news: Russian company charged in Mueller probe seeks grand jury materials
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Damage to train tracks from severe weather has suspended Brunswick, Maryland's MARC's Brunswick Line service.
In New York, the line of storms pushed through Tuesday afternoon causing havoc right at rush hour.
There were almost 50 reports of hail in states including Ohio, Pennsylvania, New York, and CT, the National Weather Service (NWS) said.
A tornado watch was issued this afternoon for upstate NY, the Hudson Valley, northeast Pennsylvania, western Connecticut, Massachusetts and southern Vermont.
Storms that ravaged parts of the Northeast and the Mid-Atlantic - and claimed at least five lives - have passed, but the risk of flooding continues Wednesday.
Much of the East will see rain in the next three days. The biggest threat for flooding will be from southern New Jersey to Virginia, where 4-8 inches of rain could fall with localized heavier amounts possible.