A gunman opened fire inside the Holocaust Museum in the nation's capital Wednesday, fatally shooting a security guard before other officers returned fire and injured the assailant, officials said.

Law enforcement officials identified the suspect to FOX News as James W. Von Brunn, who has a history of virulent racism, ties to white supremacy groups and a criminal record that includes an attempt to take members of the Federal Reserve board hostage, according to media reports and Web sites. Washington police, however, haven't publicly named a suspect.

The gunman was in critical condition Wednesday evening. His victim, 39-year-old Stephen Tyrone Johns, had served on the museum's security staff for six years.

"There are no words to express our grief and shock over today's events," the museum said in a written statement released after the shooting, adding that the museum would remain closed Thursday in Johns' honor.

Joseph Persichini, assistant director in charge of the Washington FBI field office, said the shootings were being investigated as a possible hate crime or a case of domestic terrorism.

Mark Potok of the Southern Poverty Law Center said Von Brunn's Web site has long been listed as a hate site.

Click here for photos.

When Von Brunn was captured he possessed a list he had made of lawmakers on Capitol Hill, a law enforcement officer told the Associated Press. The purpose of the list was not immediately clear, the official said.

Von Brunn, 88, was sentenced in 1983 to more than four years in prison for attempting to kidnap the Federal Reserve Board after a guard found him outside of a board meeting with a gun, knife and sawed-off shotgun.

Police said he wanted to take the board hostage because of high interest rates and the country's financial problems, MyFOXDC.com reported.

A Web site Von Brunn maintains, Holy Western Empire, carries several anti-Semitic statements, as well as comments against blacks.

Click here for more on Von Brunn's backround.

Law enforcement officials were searching a car believed to be Von Brunn's parked in front of the museum. They were also testing the vehicle for explosives, MyFOXDC.com reported.

Authorities also raided Von Brunn's home to check his computer and investigate the shooting as a possible hate crime or domestic terrorism.

David Schlosser, a spokesman for the U.S. Park Police, said the gunman entered the museum shortly before 1 p.m. and shot the security guard, before two other security guards returned fire and wounded the shooter. Both the shooter and security guard, later identified as Johns, were then sent to a local hospital, he said.

D.C. Police Chief Cathy Lanier said the gunman was carrying a rifle and used it immediately. "He raised the rifle and started shooting," she said. "The second he stepped into the building, he began firing."

Lanier told reporters the suspect appears to have been a "lone gunman" and that authorities received no prior threats.

Museum officials estimated the entire incident unfolded in approximately two minutes.

"Our hearts and thoughts go out to the security guard and his family," D.C. Mayor Adrian Fenty said at the press conference.

At the White House, just blocks away from the museum, President 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."

In a statement from Israel's government, Information and Diaspora Minister Yuli Edelstein said the shooting was "further proof that anti-Semitism and Holocaust denial have not passed from the world."

And the Council on American-Islamic Relations, a prominent American Muslim organization, said in a statement, "We condemn this apparent bias-motivated attack and stand with the Jewish community and with Americans of all faiths in repudiating the kind of hatred and intolerance that can lead to such disturbing incidents."

Police and other law enforcement, including the FBI's Terrorism Task Force, had surrounded the museum Wednesday afternoon after the gunshots.

"We heard a huge boom and we all kind of looked around," said a visitor from Chicago. After they heard more shots, she said, "We all hit the ground and definitely knew it was gunshots."

Kimberly Frank, also from Chicago, said she and her son Tyler were just finishing up their tour of the museum when she heard five shots, though she didn't initially know they were gunshots.

"I was terrified," her son said.

The Holocaust Museum is a popular tourist destination, located south of the National Mall and near the Washington Monument.

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The Associated Press contributed to this report.