Trapped motorists were rescued from swirling floodwaters in several spots, houses were struck by lightning and many roads were closed last night as fierce thunderstorms pelted the Washington area.

The storm flooded basements, forced evacuation of apartments, delayed Metrorail service and disrupted airline schedules.

With rain falling in places at a rate that meteorologists estimated at two to three inches an hour, water rose swiftly on many thoroughfares, including Swink's Mill Road in McLean, East West Highway and Sligo Creek Parkway in Montgomery County and New Hampshire Avenue in Prince George's County.

At the National Zoo, a zoo police officer was rescued late last night by D.C. emergency personnel after he was trapped by water that reached the windows of his private car.

Rescuers extended a ladder and pulled him from the car about 10:15 p.m. after outfitting him with a flotation device, said fire department spokesman Alan Etter.

Two people were rescued from a car on Rock Creek Parkway near Massachusetts Avenue NW, and two other vehicles veered from the parkway into Rock Creek near Park Road NW, Etter said.

At least one auto was swept downstream as Sligo Creek surged over its banks in the Silver Spring area, said Pete Piringer, a spokesman for the Montgomery County fire and rescue service. Areas near the creek in Prince George's County also flooded.

Flights to all three of the Washington region's major airports were delayed or canceled. A Federal Aviation Administration Web site showed that flights scheduled to arrive in the area were being held on the ground at their points of origin.

Flooding was reported in the control room at the Silver Spring station on Metro's Red Line. Two Red Line trains were halted while others proceeded slowly after the 9:45 p.m. flooding, a spokeswoman said.

"Hopefully overnight they'll have everything cleaned up and ready to go," said Cathy Asato, the spokeswoman.

In Baltimore, protective material intended for a painting project on the city's Francis Scott Key Bridge blew down, forcing the bridge to close.

Sweeping across the Washington region after a day of oppressive humidity, the storms inundated streets in low-lying areas, from Richmond in the South to Harford County, Md., in the north, and across to the Eastern Shore. The storm system also brought pouring rain to New Jersey and eastern Pennsylvania, where as much as six inches fell yesterday, according to the National Weather Service.

In the Washington region, flooded thoroughfares were reported in Calvert and St. Mary's Counties in southern Maryland, in Dorchester County on the Eastern Shore and in Baltimore.

In Prince George's, the impact appeared most severe in western and northern sections, including Adelphi, Beltsville and Laurel. Motorists were pulled from floodwaters at New Hampshire Avenue and Piney Branch Road. Water flooded the basements of at least half a dozen houses in the 8400 block of New Hampshire Avenue, said Prince George's fire department spokesman Chauncy Bowers.

Residents of at least four apartments in a building on Morris Drive in Laurel were forced to leave because of flood damage, Bowers said.

The full force of the storm began to be felt about 8 p.m., as sheets of rain began to soak lower Montgomery County and Upper Northwest Washington. Within the next hour or two, rescuers were dispatched to aid stalled motorists in Montgomery at such spots as Massachusetts Avenue at Little Falls Parkway, where three people were extricated from high water.

In Silver Spring, where Sligo Creek overflowed, rescuers saved a motorist who was in a car that, impelled by the force of the fast-moving water, "continued downstream," Piringer said.

Rescues also were made on River Road in the Somerset area, where three people who had been in two cars were brought to safety, he said.

Emergency personnel also went to the aid of motorists on Georgia Avenue near the Capital Beltway and on New Hampshire Avenue and Colesville Road near Sligo Creek, as well as on East West Highway and on Carroll Avenue near Long Branch Parkway.

No injuries were reported to those who escaped stalled cars, some with the aid of boats brought by swift-water rescue teams. However, Piringer said passengers were injured in several collisions elsewhere in the county.

He said several structures in Montgomery were reported hit by lightning. Damage was estimated at several hundred thousand dollars at a house in the 18200 block of New Hampshire Avenue in the Ashton section, Piringer said.

Flash flood warnings were issued last night for much of the area. The warning for Prince George's was extended until 1:45 a.m. today as rain continued to fall.

Despite lightning and wind gusts of as much as 30 miles an hour, Pepco said only about 600 customers were without electricity at one point late last night.