As terrorists are using social media to issue a call to arms, lawmakers are looking at ways to deal with online propaganda.

FOX News Radio's Rachel Sutherland reports from Washington:

At a House Homeland Security Committee hearing, Chairman Mike McCaul said a Jihadist tweeted about plans to attack a Garland, Texas event featuring caricatures of the Prophet Muhammad before it happened.  

(McCaul) "This attack exemplifies a new era in which terrorism has gone viral."

Michael Steinbeck with the FBI's counter-terrorism division says the agency is culling through countless tweets, looking for potential terror plots.

(Steinbeck) "Who amongst those individuals are up to no good?"

McCaul said social media is the new front in the battle against Islamic extremists.

In Washington, Rachel Sutherland, FOX News Radio.