Getting stuck in a Ku Klux Klan demonstration was not what Ronald Corner and his family had in mind when they came up from Norfolk to spend the Labor Day weekend on the Mall.

"We were sitting on a bench about 9 a.m. waiting for the museums to open when police cars started going by," said Lena Clark, Corner's wife. "My 9-year-old daughter, Jessica, said, 'That makes 10 police cars, Mommy. What's up?' We didn't know about the Klan until a police officer came by on a horse and stopped to feed him. He said, 'This is not the place to be today, folks.' "

Thousands of tourists unwittingly stumbled onto the Klan demonstration yesterday, disrupting travel plans, creating traffic and parking problems and exposing many people to a show of force they rarely see in their home towns.

"To us, a demonstration is 50 to 75 people," said Harold Miles, of Burlington, Vt. "I've never seen such a display of law enforcement in my entire life. I've already gone through two rolls of 36-exposure film."

Madison Drive between 14th Street NW and Third Street NW, normally open Sundays, was closed to all but law enforcement officers, vehicles and horses, although pedestrians could still use it. The north entrances to the museums along Constitution Avenue were closed, and police put up fences to control access to Constitution, the planned parade route.

South of Madison to Independence Avenue SW, however, the Mall looked much as it does on any summer Sunday, with a passing show of joggers, baby strollers and people sunbathing on the grass.

In the midst of everything, at the southwest corner of Constitution and 15th, an evangelical crusade from Texas set up tents for a 21-day revival that begins this week.

"We couldn't have shown up at a better time," said William Pfister, of Dallas, a crusade organizer. "One group, the Klan, is here to express their hatred for others, and the other group shows up to profess their anger. Jesus needs to be here."

Visitors to Washington usually take back memories of seeing the Washington Monument and John Glenn's space capsule. Some people in yesterday's crowd, many with video cameras, said they will also remember seeing police officers in riot gear unloading tear gas canisters and counter-demonstrators screeching angry chants. Others used the demonstration to show their children the horses or give them a firsthand lesson in freedom of speech.

"It's hard to explain to our daughters," Clark said of Jessica and Victoria, 6. "We've taught them to believe everyone is equal. But they don't understand. They think we're going to see some clowns."

Mildred Robertson, of Reading, Pa., whose visiting family was caught by surprise, said, "We have a son in the Marine Corps in Saudi Arabia, and we wonder why people like the Klan are allowed to parade in the streets when we have people like my son trying to protect this country."

As it turned out, most people on the Mall could not see anything, even after waiting for hours in the heat at vantage points such as Third Street and Madison Drive to get a peek.

Michael Stanley, who came up from Richmond only to witness the Klan sideshow, captured the essence of the day from the spectators' point of view. "A tempest in a teapot," he said.