When John Riggins tore into the end zone after a fourth-quarter, 43-yard run that put Washington's beloved Redskins ahead of Miami for the first time, the fever that had been building all week long in this football-crazy town finally exploded.

There was more Redskins' scoring to come, but Riggins' run set off an eruption of uncontained jubilation from Capitol Hill to Culpeper, from Georgetown to Jessup that promised to last till dawn's early light.

Thousands of screaming revelers ran into the streets of Washington and its suburbs, hugging and kissing each other, throwing confetti, waving flares and pounding on cars and buses. Collectively, the area was afflicted last night with what one fan called a "Redskin seizure."

For hours after the game, the foggy night sky erupted with firecrackers, shotgun blasts, whistles, car horns and demented howls of satisfaction.

In an effort to contain the celebrations, police cordoned off much of Georgetown and a four-block strip of Pennsylvania Avenue on Capitol Hill. They blocked off incoming traffic on Memorial and Key bridges, but still the crowds--singing, drinking, dancing and slapping hands--grew from hundreds to thousands.

About 75 dauntless fans scrambled atop a Metrobus as it lumbered through the throng along Wisconsin Avenue. Nearby, on M Street, a second bus with three passengers aboard was stalled helplessly as dozens in the madding crowd pounded on its sides. Others climbed to the tops of street lamps, window awnings, fire escapes--anything that wasn't moving, and some that were--to stick their index fingers into the sky and proclaim the Redskins "Number One." Two of four traffic signals at the intersection and an undetermined number of street signs fell victim to the frenzy.

Amid the delirium on Capitol Hill, Ray Bowlding, a repairman for Pepco, lay on his back in the middle of Pennsylvania Avenue, kicked his heels into the air, and announced: "This town has never been this way before. The Redskins have brought us so close together. Never mind everybody's everyday problems. This is Super Bowl Town."

Around midnight at the Tune Inn nearby, Peter Hintze surveyed the bedlam and said: "Ya know what? Fifty percent of the town's work force will not be in tomorrow. And ya know what? The other 50 percent won't care."

D. C. police listed about a half dozen or so "nonserious injuries," a dozen arrests and some widely scattered reports of window breakage and theft during the hullabaloo. For the most part, however, officers appeared to be acting more like players than referees--blasting their sirens and making little attempt to break up the carnival. District police Officer Mike Turner said authorities planned "just to let them have a good time, more or less anything goes," except destruction of property and assaults. "Drinking in public and by minors we're overlooking," he said.

And after all, what the hell, this city seemed to be saying, the Redskins are Super Bowl Champions.

The team that wasn't supposed to win, the team that spent a strike-interrupted season searching for respect, managed to win America's most ballyhooed sporting event, and with it, the championship of professional football.

The people of Washington--united with a rare sense of community and belonging ever since the Redskins defeated the Dallas Cowboys a week ago--could hardly contain themselves last night.

Wearing an Indian war bonnet with burgundy and gold feathers streaming down his back, Mark Wallach, a bartender at Annie Oakley's bar in Georgetown, dashed out into the street, blocked cars, grabbed pedestrians and prepared the intersection of Wisconsin and M Streets for the coming madness.

Hundreds of beer-drenched celebrants followed the victory-crazed bartender. Waiters from the Pizzeria Uno came out with bottles of champagne, uncorked them in the middle of the intersection and passed them around. A special detail of police tried vainly to keep traffic moving, but within five minutes the streets succumbed to 'Skins-lock.

Some riotous fans at the Wisconsin Avenue intersection jumped on top of a blue four-door car with Virginia license plates and pounded dents in the roof, hood and trunk as the driver looked on helplessly.

Unable to stop them, he climbed on top of his dented car and joined the mob. Someone handed him a beer.

By midnight, there wasn't a dent-free car to be seen within blocks of the intersection.

On Pennsylvania Avenue SE, outside the Hawk and Dove bar, scores of people were seen jumping up and down, making Indian-like noises ("woo-woo-woo-woo"), in an imitation of the Redskins' "Fun Bunch" receivers who did the same thing last night in the end zone at the Rose Bowl.

From the moment of Riggins' fourth-quarter touchdown run, the Capital Centre broke out in pandemonium. The 1,000 fans who showed up for a free viewing of the game in the 19,000-seat arena stamped their feet and hugged total strangers.

"We beat 'em, we beat 'em. . . we're the champs," yelled Larry Overton, a school teacher from the District who held his young son, Larry Jr., in his lap. Suddenly Overton burst into tears. "I have never. . . I have never. . . .," he sputtered, "The Redskins are the best thing we have in this town. Every week they try, they do their best and they deserve this."

At the Sheraton Washington Hotel, where the Cotillion ballroom had been transformed into a mini-stadium complete with bleachers, goal posts, a giant scoreboard and cheerleaders, the early civility of a crowd that had been nibbling on shrimp and carrot cake turned to unrestrained screaming. Strangers kissed each other.

Along a five-mile stretch of Rte. 50 in Prince George's County after the game, little knots of Redskins fans waved pennants, held up signs, jumped into the air and reached out toward people whizzing by in their cars. Cars honked and winked their high beams at each other.

At Massachusetts Avenue and 12th Street NW, nine whooping teen-agers stuffed in a Volkswagen Rabbit communed for a few moments with two middle-aged couples in a staid Buick sedan as both cars waited for a traffic light. The drivers honked to each other, the passengers reached out and touched hands and cheered each other and the Redskins.

In Camp Springs, celebrants who paid $10 each for the privilege of watching the Super Bowl at one of Joe Theismann's two area restaurants formed a giant human chain when the game ended. Dale Rinker, an Air Force master sergeant who was the most frenzied man in the bar, led about 150 people who twisted and danced around tables, over chairs, singing "Hail to the Redskins."

"I'm only drinking club soda, too," Rinker said, waving a stick on which was skewered a small, mutilated toy dolphin.

Crowds began forming in Georgetown as early as three hours before game time. With war-painted faces and Indian headdresses, in hog T-shirts and gold scarves, they jammed bars and jostled each other for clear views of television sets. The manager of the Bayou on K Street was forced to close his doors during the first half because of overcrowding. Mr. Henry's on Wisconsin Avenue placed a small portable color television set in its window for passers-by who couldn't get inside.

A full hour before game time, at a converted dairy barn in Oxon Hill, 50 very loud and rambunctious members of American Legion Post 248 convened to eat, drink beer (gallons of it), stomp their feet and sing "Hail to the Redskins."

Loudest among the screamers at gametime were members of the John Low softball team who decided to watch the game there because, explained Chuck Sanford, a team member, "We'd be kicked out of anywhere else."

There was a thirst, literally, for revenge on the part of Fred Carpenter, who 10 years ago--for Washington's last Super Bowl appearance--bought 60 cases of beer for the Legion hall only to find the game too boring and depressing for boozing. "We couldn't drink a damn bit," said Carpenter.

Last night, during the first half as the Dolphins led the Redskins, pre-game jubilation quickly turned to bad nerves.

"Will you be quiet," yelled Peck Norris to his son Steve, who'd been bemoaning Miami's first touchdown. "The game's not over yet. The 'Skins are going to eat the fishes."

After Theismann completed a pass to Alvin Garrett for Washington's first touchdown, Norris felt confident enough to get up and go to the bathroom. He got back to his seat just in time to see the Dolphins' return man, Fulton Walker, run back a Washington kickoff for a touchdown. "Oh, s---," he hollered, "now we've got to start all over again."

All day Sunday, Washington prepared, with elaborate meals, rivers of liquor and an occasional prayer, for the evening game.

At the 12:45 p.m. mass at St. Matthew's Cathedral, a priest drew an analogy during his sermon between Jesus walking through the crowds in Nazareth and running back John Riggins breaking through tacklers. The priest asked that worshipers remember the Redskins in their prayers.

Twenty miles outside the Beltway in Calvert County, Md., three live hogs (scheduled for butchering come Tuesday) were part of the attraction at a game-watching party at Tom Hamlen's home.

"These hogs can get nasty," said Hamlen, an electrical engineer who invited 21 people to come to his house, drink, pet the hogs and wait for the game. " The hogs seemed to be very content at my party. They ate a couple of burgundy and gold banners, and washed them down with a couple of beer cans."

Contributing to this report were Washington Post staff writers Lloyd Grove, Molly Moore, Keith Richburg, Saundra Saperstein, Edward D. Sargent and Tom Vesey, and special correspondent Rick Allen.