A man arrested over the shooting and wounding of a security guard at the headquarters of the anti-gay Christian lobby group the Family Research Council made a negative comment about the group before opening fire, a police official has said.

Police said a man entered the front lobby of the Family Research Council in Washington DC around 10:45 a.m yesterday and argued with a security guard before shooting him.

A police official identified the suspect to the Associated Press as Floyd Corkins II.

Corkins, 28, is a volunteer at the DC Center for the LGBT Community. Its executive director David Mariner said: “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.”

Fast food chain Chick-fil-A has come under-fire of late for giving millions of dollars to the group to fund its anti-gay marriage campaigns.

Brian Brown, president of another anti-equality group called the National Organization for Marriage said: “Today’s attack is the clearest sign we’ve seen that labeling pro-marriage groups as `hateful’ must end.”

White House spokesman Jay Carney said: “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,”

Anti-marriage equality Republican presidential candidate Mitt Romney said: “There is no place for such violence in our society. 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.”