Washington, D.C ? An 88-year-old gunman with a violent and virulently anti-Semitic past opened fire with a rifle inside the crowded U.S. Holocaust Memorial Museum on Wednesday, fatally wounding a security guard before being shot himself by other officers, authorities said.

The assailant was hospitalized in critical condition, leaving behind a sprawling investigation by federal and local law enforcement and expressions of shock from the Israeli government and a prominent Muslim organization.

Washington Police Chief Cathy Lanier said the gunman was “engaged by security guards immediately after entering the door” with a rifle. “The second he stepped into the building he began firing.”

Law enforcement officials said James W. von Brunn, a white supremacist, was under investigation in the shooting and that his car was found near the museum and tested for explosives. The weapon was a .22-caliber rifle, they added. They spoke on condition of anonymity, saying they were not authorized to discuss the investigation just beginning.

When von Brunn was captured he possessed a list he had made of lawmakers on Capitol Hill, according to another law enforcement officer who requested anonymity. The purpose of the list was not immediately clear, the official said.

The dead guard, Stephen Tyrone Johns, 39, was a six-year veteran of the facility who lived in Temple Hills, Md. Museum Director Sara Bloomfield said he “died heroically in the line of duty.”

At the White House, just blocks away from the museum, President Barack Obama said: “This outrageous act reminds us that we must remain vigilant against anti-Semitism and prejudice in all its forms. No American institution is more important to this effort than the Holocaust Museum, and no act of violence will diminish our determination to honor those who were lost by building a more peaceful and tolerant world.”

Von Brunn has a racist, anti-Semitic Web site and wrote a book titled “Kill the Best Gentiles,” alleging a Jewish conspiracy “to destroy the white gene pool.” Writings attributed to von Brunn on the Internet say the Holocaust was a hoax. “At Auschwitz the ‘Holocaust’ myth became Reality, and Germany, cultural gem of the West, became a pariah among world nations,” one says.

In 1983, he was convicted of attempting to kidnap members of the Federal Reserve Board and served more than six years in prison. He was arrested two years earlier outside the room where the board was meeting, carrying a revolver, knife and sawed-off shotgun. At the time, police said von Brunn wanted to take the members hostage because of high interest rates and the nation’s economic difficulties.

The museum was crowded with schoolchildren and other tourists at the time of the attack, but they all escaped injury in the outburst of violence.