...are going fast.

According to the Denver Post: More than 24,000 visitor passes to the new Sept. 11 memorial are gone—distributed Monday in just the first hours after the ticket website went live.

The online reservation system for the tickets was up at 9 a.m., and 5,000 were secured for various dates in just the first hour of operation.The Kansas City Star reported that there only were 5,000 passes but the Denver Post reports differently.

Passes to the memorial are free, the Post says, and officials said they expect them to be in heavy demand as 9/11 approaches.

Reservations are required because the parts of the memorial plaza open to visitors can only hold 1,500 people at a time.

You can check out the memorial site here.