By Ian Simpson

WASHINGTON (Reuters) - Powerful thunderstorms packing heavy rain and high winds lashed the U.S. Middle Atlantic region late on Tuesday, killing one person, snarling travel and cutting off power to hundreds of thousands of customers.

The fast-moving band of storms stretching from Virginia to southern New Jersey dumped up to one inch (2.5 cm) of rain in less than an hour in some places, said Jim Hayes, a National Weather Service meteorologist in College Park, Maryland.

"The storms were intense but they were moving pretty quickly," he said.

Police in Montgomery County, Maryland said a 79-year-old man died after his pickup truck hit a tree that had fallen across the roadway, about 30 miles (48 km) north of Washington D.C.

Private forecaster AccuWeather said the storms would reach into northern New England through the evening as a cold front intersected with hot and humid air.

Winds of up to 70 miles per hour (113 kph) were recorded in southern New Jersey, and the line of storms stretched westward into West Virginia, Kentucky and Tennessee.

About 74,000 homes and businesses were without power in northern Virginia and in the Washington and Baltimore areas, power companies reported.

About 82,000 New Jersey customers of PSEG power company were without electricity, and more than 400,000 homes and businesses in the Philadelphia area were dark.

The bad weather prompted Amtrak, the U.S. passenger rail service, to suspend services between Washington, Philadelphia and Harrisburg, Pennsylvania, for about an hour.

Flightaware.com, which tracks airline flights, said more than 200 were delayed or canceled at each of New York's LaGuardia, Newark's Liberty International and Philadelphia International airports.

(Reporting by Ian Simpson; Additional reporting by Curtis Skinner in San Francisco; Editing by Alan Raybould and John Stonestreet)