A day after a New York man was indicted on charges of trying to provide support to the Islamic State, top federal officials expressed concern to Congress about the reach the terrorist group could have via the Internet to inspire Americans to carry out  domestic attacks.

“Someone can do it in their pajamas in their basement,” FBI Director James B. Comey told the House Homeland Security Committee during a hearing Wednesday morning. “These are the homegrown violent extremists that we worry about, who can get all the poison they need and the training they need to kill Americans, and in a way that is very hard for us to spot.”