The incident could be handled as an incident of domestic terrorism depending on the suspect's motivations, an FBI spokeswoman told reporters on the scene.
NBC and ABC7 identified him as 28-year-old Floyd Corkins of Virginia. Fox News obtained photos of the man, apparently taken by a witness, that show the suspect in handcuffs and his bloody shirt fully unbuttoned.
A few hours after the incident, FBI officials completely closed off the block surrounding FRC's headquarters -- which is located in the busy Chinatown section of downtown D.C. -- due to a report of suspicious package inside the building. Authorities gave the all clear about an hour later.
FRC, which hosts the annual Values Voter Summit, was controversially labeled as a "hate group" by the Southern Poverty Law Center because its beliefs and practices "attack or malign an entire class of people, typically for their immutable characteristics."
The organization had shown its support for Chick-Fil-A, the fast food restaurant which came under fire from gay rights groups because of its CEO's opposition to gay marriage rights. Several LGBT organizations condemned the shootings on Wednesday.