Corkins had been volunteering for about the past six months at The DC Center for the LGBT Community, said David Mariner, executive director of the community center, in Northwest Washington. He usually staffed the center's front desk on Saturdays, and his most recent shift was about two weeks ago.
"He always struck me as a kind, gentle and unassuming young man. I'm very surprised that he could be involved in something like this," Mariner said.
Authorities seized Corkins' car at a northern Virginia Metro station, and were going door-to-door interviewing neighbors, several of whom spoke highly of the family.
"They were always so sweet and so nice," said Stephanie Meyer, who lives a few doors down. "They are awesome people. We never had any issues."
According to a U.S. Defense Department official, Corkins is not a member of the Air Force, but he may have lived at Andrews Air Force base in some other capacity in the past, possibly as a dependent or family member. The official spoke on condition of anonymity because the official was not authorized to provide personal information.
Amy Biondi and her husband Steve were visiting Washington from Long Island with their daughter and a friend and tried to ask officers for help with a parking meter when they were told there was a situation they had to deal with. The door to the FRC was opened, and an officer could be heard repeatedly shouting, "Put the gun down, put the gun down."
"Next thing you know there are police officers swarming the area," said Biondi, 45, a massage therapist from St. James, N.Y.
The family didn't get a close look inside, but they said the man that officers were talking to seemed to comply immediately.
Groups aligned with conservative causes lambasted the shooting, but so did a coalition of about two dozen organizations promoting gay, lesbian and transgender rights, which said it rejected and condemned the attack.
White House spokesman Jay Carney said the president, who was traveling in Iowa Wednesday, was informed of the shooting shortly after 1 p.m.
"The president expressed his concern for the individual injured in the shooting and his strong belief that this type of violence has no place in our society," Carney said.
Romney said in a statement that he was appalled. "There is no place for such violence in our society," he said. "My prayers go out to the wounded security guard and his family, as well as all the people at the Family Research Council whose sense of security has been shattered by today's horrific events."
The headquarters of the FRC is in the city's bustling Chinatown neighborhood, near the Verizon Center, the Smithsonian National Portrait Gallery and several museums, restaurants and shops.
In the past month, the FRC has forcefully defended Chick-fil-A President Dan Cathy for his remarks in opposition to gay marriage.
Mariner said he did not know Corkins well or have any conversations with him about the Chick-fil-A controversy or other political issues of interest to the gay community.
"I really only talked to him about volunteering, so I couldn't say anything about anything else," Mariner said.
Associated Press writers Ben Nuckols and Lolita Baldor in Washington and Matthew Barakat in Herndon, Va., contributed to this report.
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