WASHINGTON -- James Wenneker von Brunn spent much of his adult life on the seething fringes of racial politics, fulminating about blacks and blaming Jews for everything from communism and syphilis to the "hoax" of the Holocaust.

Police say that rage propelled the 88-year-old Mr. von Brunn into the lobby of the United States Holocaust Memorial Museum along the Mall yesterday, where he gunned down a security guard before being shot himself.

James Wenneker von Brunn

The attack sent visitors diving for cover, some seeking safety behind the doors of exhibit rooms filled with photographs and artifacts attesting to a mass murder nearly 70 years ago -- a genocide Mr. von Brunn spent much of his life denying.

"There were younger people crying, teenagers crying," said Randy French, a stockbroker from San Antonio, Texas, who was visiting with his wife and teenage sons. "There were bunches of school groups. Little ones and teenagers, too."

The guard, identified as Stephen Tyrone Johns, died shortly after being shot. He was black, a minority group frequently targeted in Mr. von Brunn's online diatribes. One co-worker, who spoke on condition of anonymity because staff were instructed not to speak to the press, called Mr. Johns "a gentle giant" who stood 6 feet, 8 inches tall and weighed 370 pounds.

The museum will be closed today in honor of Mr. Johns.

Mr. von Brunn was in critical condition at a Washington hospital.

"He didn't just happen to go to the Holocaust Museum," said Deborah Lipstadt, a Holocaust scholar who was working at the museum on a year-long fellowship. "This was not a perchance crazy killing. This was a guy who was out to kill people -- either blacks or Jews -- and to kill people who were at the museum."

Ms. Lipstadt, whose 1993 book "Denying the Holocaust," explored the world of anti-Semites who attack the historical truth of the mass killing of Jews in World War II, said she was in the middle of a meeting at the museum when she heard gunfire in the lobby.

"At first I thought it was a piece of equipment that had fallen. Then there were shots. Then shots were returned. Then you heard screaming. Then someone looked out the room and saw that people were being herded into bathrooms and into off-site safe places," she said.

Police and FBI closed off a one-block area around the museum. Mr. von Brunn's car was found parked nearby and police searched it for explosives. None were found. One law enforcement source said FBI agents had located a list compiled by Mr. von Brunn that named roughly a dozen other targets.

Mr. von Brunn's denial of the Holocaust was marked by a chapter devoted to that subject alone in his anti-Jewish book.

"Holocaust lies were invented for the following reasons," he wrote in his self-published book that stretches for more than 400 pages. "Extort 100+ billion dollars in 'reparations' from Germany. Discredit western civilization before the world. Paralyze the west's will to act in its own interest. ... Allow Jews to dominate U.S.A."

An obscure and angry man who often harkened back to his days as a Navy PT boat captain, Mr. von Brunn was a regular on various extremist Web sites and, before that, at the occasional political meeting. The Southern Poverty Law Center said he worked for a time for Noontide Press, a Holocaust denial publishing house founded by political extremist Willis Carto.

Mr. Carto yesterday said he did not recall Mr. von Brunn.

Mr. von Brunn spent several months in northern Idaho six years ago, according to law enforcement sources, and was interviewed at one point by "The Zundelgram," a newsletter organized on behalf of a German-born Holocaust denier who was prosecuted in Canada.

Until yesterday, Mr. von Brunn was known only to a handful of experts who monitor extremists and their organizations. "If you could make a top 100 in the world of white supremacy, he was not someone who rated that," said Ken Stern, director of research for the American Jewish Committee.

Yesterday, FBI agents searched Mr. von Brunn's apartment in Annapolis, Md., and a spokesman for the District of Columbia FBI office said the attack was being investigated as a possible hate crime.

His one brush with wide publicity came on Dec. 7, 1981, when, toting a sawed-off shotgun, .38-caliber handgun, a bowie knife and coil of rope to bind his prisoners, he entered the Federal Reserve Building in an attempt to "arrest" its board of governors, including then-Chairman Paul Volcker.

"I intended to bind their hands and persuade them to appear on television," Mr. von Brunn wrote later. "There, on camera, I intended to read to the American public my indictment of these treasonous liars."

Instead, Mr. von Brunn ended up surrendering his weapon to a guard. He was indicted on charges of attempted kidnapping, burglary, assault, and weapons violations and spent six years in federal prison.

Yesterday's attack is the fourth violent outburst with political undertones to take place in the United States this year.

In April, Richard Poplawski was charged with murder, accused of lying in wait with a shotgun and assault rifle and gunning down three Pittsburgh police officers who answered a call to evict him from his mother's home in Stanton Heights. Mr. Poplawski had posted a number of racist screeds on Stormfront, a white supremacist Web site.

Last month, George Tiller, a Kansas abortion provider, was shot to death in his church.

Last week, William Andrew Long, an Army private, was gunned down outside a recruiting office in Arkansas. Another soldier was wounded. The suspect told authorities he was a Muslim convert and considered the killings justified because of the U.S. role in the Middle East.

The White House press office issued a statement saying President Barack Obama had been notified of the attack at the Holocaust Museum.

Last week, Mr. Obama visited the Buchenwald concentration camp site in Germany and declared, "There are those who insist the Holocaust never happened." He added, "This place is the ultimate rebuke to such thoughts, a reminder of our duty to confront those who would tell lies about our history."

Mr. von Brunn, in one of his writings, bemoaned Mr. Obama's election, saying the new president was not born in the United States and was ineligible to hold office.