An American white supremacist opened fire at the US Holocaust Memorial Museum Wednesday, killing a security guard before being shot himself, according to initial reports. The shooter was named as James Von Brunn by a law enforcement official, pending confirmation and speaking on condition of anonymity, who noted that his car had been found near the museum. Both Von Brunn and the security officer, named as Stephen T. Johns, were rushed to hospital following the shootout, which took place at midday. Von Brunn was described by officials as in "grave condition." A Washington Fire Department spokesman said that a third person had been lightly wounded in the exchange, in which two officers fired back at the assailant. Following the attack, President Barack Obama reacted with shock, saying that the act demonstrated the need to fight anti-Semitism. "I am shocked and saddened by today's shooting at the US Holocaust Memorial Museum," he said in a statement. "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. "Today, we have lost a courageous security guard who stood watch at this place of solemn remembrance," the statement continued. "My thoughts and prayers are with his family and friends in this painful time." Bystanders described a scene of fear and chaos as they heard security officers yell at hundreds of students, tourists and museum staff to flee the premises. Public safety officers then secured the perimeter and cut off vehicles from the site. FBI agents are helping with the investigation, as authorities said they were checking for possible terror connections. Washington Police Chief Kathy Lanier said the police had received no information or threats that such an attack was in the offing. She refused to confirm that Von Brunn was the lead suspect during a press conference following the shooting. Von Brunn is a well-known white supremacist, Mark Potok of the Southern Poverty Law Center told CNN, referring to a Web site and publications he produced over several years in which he has "raged" against Jews and blacks. He noted that Von Brunn had been arrested in the past in connection to hate crimes. But some of the witnesses to Wednesday's shooting said they didn't believe the shooter to be elderly, though Von Brunn is in his late 80s. However, they also noted that they found themselves amid chaos and confusion as museum-goers tried to figure out what to do. "People were running as fast as they could... People were on the floor," said 19-year-old Maria Hernandez, who heard the shots and saw blood covering the ground. "It was just chaos everywhere." She also heard this "very angry yell" coming from the perpetrator, while the guards were telling him to drop his weapon and get down on the floor. Karen Unruh, who was waiting in line with her two grandsons when the shooting started, heard a "bang, bang, bang" and worried that they would be the next victims, so "we just hit the floor." Standing among the throng of reporters and curious tourists outside the museum following the attack, she expressed shock at what happened. "I just can't believe this is happening to us in America." Ora Mois, who was visiting Washington from Kfar Saba, also couldn't believe that she found herself amid such violence in the US. "In Israel, we've gotten used to this, but here? It's the American dream, to come here, to travel, but not like this." But her brother Moti Shair said he wasn't surprised. "People are looking for Jews, wherever they are, to make a point," he said. "It's terrible. It reminds me of some sad memories from the past. They're still looking for Jewish targets." Several Jewish and Israel groups expressed alarm at the news. "We are shocked and saddened by today's shooting incident at the US Holocaust Memorial Museum in Washington. The Embassy of Israel condemns this attack and is closely following the situation," the embassy said in a statement. Strategic Affairs Minister Moshe Ya'alon, who was concluding a two-day visit to Washington, was not believed to be in the area, as a visit to the museum was not on his itinerary. The Holocaust Museum also put out a statement emphasizing its concern for the injured security officer, before he passed away. "Our thoughts and prayers go out to the officer and his family," it read. The statement indicated the facility was expected to reopen Thursday. US President Barack Obama was saddened by the shooting at the museum, which is near the White House, a spokesman said. In Jerusalem, Diaspora Affairs Minister Yuli Edelstein said, "This evening's incident is, regrettably, yet another proof that anti-Semitism and Holocaust denial are still alive and well. Israel must fight these phenomena in the domestic arena, in the international arena, in the legal arena, in academia and in the media, and must demand that the rest of the world say 'No!' to incidents such as this." The Yad Vashem Holocaust Memorial expressed shock on Wednesday at the "appalling" shooting attack on the US Holocaust Memorial Museum in Washington. Yad Vashem spokeswoman Iris Rosenberg said in a statement that "the museum, in addition to being a memorial to the victims of the Holocaust, is dedicated to educating against this kind of hate. His target makes this shooting that much more heinous." Yad Vashem Chairman Avner Shalev spoke to the Washington museum's Director Sara Bloomfield to express support, and deep empathy, to her and all the museum staff. The shooting was also condemned by the chief Nazi hunter of the Los Angeles-based Simon Wiesenthal Center. "On many levels it is a very symbolic target, and it is not surprising that someone who espouses White supremacy would want to attack an institution like that, since Holocaust museums are the antithesis of this person's racist ideology and anti-Semitism," said Dr. Efraim Zuroff, the organization's Israel director. He noted that the fact that the suspected shooter is 89 years old reinforces the organization's view that in terms of bringing Nazi war criminals to justice, age is not an issue. He added that the Wiesenthal Center in California has been the target of threats and violence, as well as actual property destruction. Etgar Lefkovits and AP contributed to this report.