PHILADELPHIA (AP) — 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.