The new 100$ bill, stolen in Philadelphia before entering circulation, FBI said

Associated Press/FBI - This undated image provided by FBI shows the newly designed $100 bill. The FBI is reporting an unusual heist of some of the bills, which aren't going into circulation until next year. Agent Frank Burton Jr. says the cash was stolen from a plane that arrived at Philadelphia International Airport around 10:25 a.m. Thursday, Oct. 11, 2012, from Dallas. (AP Photo/FBI)

The FBI is reporting an unusual heist of some newly designed $100 bills that aren't going into circulation until next year.

Agent Frank Burton Jr. says the cash was stolen from a plane that arrived at Philadelphia International Airport around 10:25 a.m. Thursday from Dallas.

Investigators said these Benjamins are easy to spot. The new bills have sophisticated elements to thwart counterfeiters, like a disappearing Liberty Bell in an orange inkwell and a bright blue security ribbon.

The FBI said a "large amount" of bills were stolen, but agents aren't giving specifics.

The theft was reported by a courier service transporting the C-notes when the shipment arrived Thursday afternoon at the Federal Reserve Building in East Rutherford, N.J. Officials then discovered some of the money was missing.