It happened around 10:24 Sunday morning off of Petercheeseman Road across from the Hickstown Community Park.
The victim was riding dirt bikes with her brother when she crashed and fell. Police say her brother was unable to stop his bike from striking her.
The female victim was found about 200 yards into the wooded area. She suffered injuries to her abdomen and her back.
The victim was taken to Cooper University Hospital. Her condition is unknown.
Gloucester Township Police continue to investigate.