"Your parents' al Qaeda was a very different model than the threat we face today," Comey said at a counterterrorism conference in New York City, according to Reuters.

He said the Federal Bureau of Investigation currently has "hundreds" of investigations in all 50 states involving potential Islamic State-inspired plots. 

Read alsoObama: We will destroy ISIL and anyone else who tries to harm usAs UNIAN reported earlier, Tashfeen Malik, 29, and her husband, Syed Rizwan Farook, 28, stormed a party in San Bernardino, California, on Wednesday, opening fire with assault-style rifles and killing 14 people. The pair were killed a few hours later in a shootout with police.