plots to attack here in the united states. the fbi says it has a number of investigations going nationwide. some have already resulted in arrests. and the most recent came today when the fbi says an agent was attacked right here in new york. nbc justice correspondent pete williams has more. >> reporter: fbi agents say when they went to this house in staten island early this morning to conduct a search, the 21-year-old man inside lunged at them with this kitchen knife, repeatedly trying to stab an agent in the chest. body armor prevented serious injury. that man, fareed mumuni, was charged today with trying to kill a federal officer. after his arrest, prosecutors say he admitted being a fervent supporter of isis who wanted to join isis fighters overseas and said if he couldn't get there he would attack any police who tried to stop him. the latest in a surge of terror-related cases that has the fbi scrambling nationwide. >> there are more cases out there. there are more americans out...