Authorities on Tuesday continued searching the Brooklyn home of the man accused in Monday's attempted terror attack under the Port Authority Bus Terminal in Manhattan.

After searching the Mill Basin, Brooklyn home of 27-year-old Akayed Ullah, investigators said they believe he was most likely radicalized in 2014 and that he carried out the attack in the name of the Islamic State group.

Investigators say they found bombmaking materials at the home. They say Ullah filled the pipe bomb with metal screws and that he planned the attack for a weekday to maximize the number of casualties. Three people, in addition to Ullah, were injured when the bomb went off.

"Ullah admitted that he began researching how to build bombs about a year ago and had been planning this particular attack for several weeks," said U.S. Attorney Joon Kim.

Ullah was charged in Manhattan federal court with terrorism and explosives charges, among others.