It happened in the 1200 block of Gloucester Road in Monroe Township just before 3:00 p.m.
Officials say three workers were on the roof of a building under construction when they fell about 20 feet to the ground.
One person was flown to Cooper Medical Center. The other two were taken to area hospitals by ambulances.
There was no immediate word on the conditions of those involved.
The circumstances of the accident are under investigation.
