The man who reportedly shot and wounded a security guard at the headquarters of a conservative Christian lobbying group Wednesday voiced opposition to the organization's work before opening fire, a law enforcement official said.

Police said the man entered the lobby of the Family Research Council in Washington around 10:45 a.m. Wednesday, began arguing with a security guard and then shot him in the arm, the Associated Press reported. The gunman was subdued by the guard and others and taken into custody but had not been charged as of Wednesday evening.

Another law enforcement official identified the man as Floyd Corkins II, and authorities were interviewing his neighbors in Herndon, Va., near Washington. Both officials spoke on the condition of anonymity because they were not authorized to discuss the investigation.

Corkins, 28, had been volunteering recently at a community center for lesbian, gay, bisexual and transgender people.

The Family Research Council strongly opposes gay marriage and abortion and says it advocates "faith, family and freedom in public policy and public opinion."

The guard, Leo Johnson, was in stable condition in a hospital and was being interviewed.

Corkins had been volunteering for about six months at The DC Center for the LGBT Community, said David Mariner, its executive director. 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.

Though authorities did not give a motive, advocacy groups condemned the violence, with some casting it as a hate crime.

"Today's attack is the clearest sign we've seen that labeling pro-marriage groups as 'hateful' must end," Brian Brown, the president of the National Organization for Marriage, said in a statement.

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.

Republican presidential candidate Mitt 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."