Alexander Ciccolo, 23, of Adams, Mass., was taken into custody on gun charges after buying two pistols and two rifles from an undercover FBI confidential informant, federal officials said. In a search of his apartment, officials reported they found it loaded with possible bomb-making equipment including a pressure cooker, a variety of chemicals, an alarm clock, along with “attack planning papers” and “jihad” paperwork. FBI agents said he used the name Abu Ali al-Amriki and neighbors said he was a recent convert to Islam.

“This is a very bad person arrested before he could do very bad things,” one senior federal official briefed on the arrest told ABC News.

According to the FBI, Ciccolo attempted to stab a nurse in the head with a pen during a routine screening, “leaving a hole in the nurse’s skin.”

An FBI affidavit said Ciccolo initially planned to travel to “another state” and used a pressure cooker bomb “to conduct terrorist attacks on civilians, members of the U.S. military and law enforcement personnel.”