At least two persons were killed here yesterday as high winds and devastating thunderstorms swept across the Washington area, uprooting trees, tearing off roofs and cutting off electricity to about 180,000 families.

One of the victims, an Air Force colonel, was killed when he was struck by a falling, windblown tree limb at Fort McNair, in Southwest. The other was drowned after his sailboat capsized in the Potomac River.

Spawning at least one confirmed tornado, the storms ripped into many spots with winds of more than 60 miles an hour, leaving roads and streets across the area strewn with roofing shingles, splintered trees and fallen electric power lines.

The storms, described as among the most severe here in years, thundered out of blackened western skies about 4 p.m. and during the next two hours spread injury, damage and disruption throughout the area.

Traffic was blocked in many places. Boats overtuned both in the river and at moorings. Trees smashed into cars and houses. Suitcases were hurled from baggage carts onto the National Airport tarmac. Part of a roof was ripped from a home on 13th Street SE. A portion of the roof of a high-rise in Alexandria was torn off, and fell into a single family house nearby. The house was heavily damaged, but no injuries were reported.

A 45-foot trailer used as a Metro subway office on the platform of the National Airport station was hurled by the wind onto the tracks. Two men were injured, and train service was disrupted.

The widespread interruption of electricity -- at one point a third of the homes in Northern Virginia were without power -- cancelled an opera, blacked out a television station covering the U.S. Open golf tournament for a few minutes just as the leaders were about to putt, and was blamed for several minor auto accidewnts at intersections where traffic signals no longer functioned.

Both National and Dulles International airports switched to standby power systems. Dulles cut in its diesel generator. National's diesel generator failed to operate and the airport restored to battery power.

All or part of the District of Columbia and Alexandria police radio communication systems were knocked out for part of the afternoon. Fairfax County sent portable radios to Alexandria to help out.

At the First Church of the Nazarene on 16th Street NW, the 6 p.m. service was held by candlelight.

But at the Wolftrap Farm Park for the performing arts, the show did not go on.

With electricity cut off, last night's sold-out performance of a highly acclaimed production of the opera "Aida" was cancelled.

A spokesman for the Virginia Electric and Power Co. reported at 2 a.m. today that about 22,500 customers in Northern Virginia remained without power. The figure was down from the peak of 110,000 who lost electricity as lightning struck transformers and falling tree limbs tore through power lines.

Between 40,000 and 50,000 customers still lacked electricity early today in the District and the Maryland suburbs, according to a spokesman for the Potomac Electric Power Co. Earlier, the figure had been about 70,000. tPepco said 97 emergency repair crews were at work last night, with workers having been summoned from as far away as Charleston, W.Va.

Vepco officials said they did not expect to restore service completely until "mid-morning." No information about full restoration of Pepco service was immediately available.

The victim in the fatal accident at Fort McNair was identified as Col. Walter R. Milliken, 54, of 6805 Vantage Dr., Alexandria.

According to D.C. police, Col. Milliken was among 400 persons at a "get together" for a new class at the National Defense University located at the post, when the storm suddenly struck.

Witnesses heard a loud cracking sound from one of the stately trees that line the grassy guadrangle to the north fo the Defense University building.

They looked up to see a limb being torn from the tree and flung by the wind. Col. Milliken was walking away from the building when he was struck by the limb and apparently killed instantly.

The second death occurred on the Potomac south of the Woodrow Wilson Bridge, near Piscataway Creek, when a sailboard with four persons aboard capsized in the high wind.

A boat sent from the Alexandria-based Coast Guard cutter Capstan helped right the sailboat and rescue three of the four aboard.

The victim was found snarled in the boat's rigging. His name was not immediately available.

One of those injured at National Airport, when the trailer used by Metro station attendants overtuned, was identified as Carl Jacobson, of Stafford, Va.

Jacobson, 37, who was at his desk when the trailer toppled, was taken to the National Orthopaedic Hospital in Arlington and released after treatment for minor injuries.

The other injured man was identified as Edward Hensley, of Laurel, a Federal Aviation Administration fireman who was climbing up the side of the overturned trailer when a board collapsed under him. He was taken to the hospital and treated for bruises and lacerations.

In the Alexandria incident, portions of the roof of a 15-story high-rise at 4600 Duke St. blew off and heavily damaged a home at 111 S. Jordan St. owned by Andy Andersen.

Andersen and his wife, Gloria, were visiting friends when a section of their $62,000 house was suddently pounded into rubble. Andersen tried later to enter the wrecked premises to obtain needed medication, but was restrained by firemen. Firemen later entered and recovered the medicine safely.

Renate Benjamin, 14, who lives next door, was in her backyard at the time, and said the flying chunks of roof barely missed her.

"All of a sudden there was this big whoosh, and then what sounded like an explosion," she said.

In addition to damaging the Andersen home the debris tore apart a shed outside the Benjamin house.

"I ran inside the house," she said "I was screaming. My mind just went blank when I though it (the debris) almost hit me."

The storm damage "looks like a bomb hit," said a resident of the Laurel Oaks Drive section of Bethesda.

"It sounded like that railroad train sound . . . the roar that a train makes," said Bob Mylod of Sequoia Court in the Parklawn section of Fairfax County, who described the storm in his area, which ripped off a straight row of treetops, as a tornado.

National Weather Service forecaster Chet Henricksen confirmed the touchdown of the tornado, which appaently caused no major damage. Another report of a tornado, in the Sterling Park area of Loudoun County, could not be immediately confirmed, he said.

Henricksen said the storms developed swiftly yesterday over the northern Shenandoah valley on the forward edge of a southeastward-moving cold front.

Temperatures here plunged more than 20 degrees after the storm arrived, falling within about two hours from the day's high of 93 degrees to the 68 degrees recorded at 6 p.m.

The arrival of the front should bring cooler weather today, Henricksen said. Showers are likely, but are not expected to be severe.