They are asking any neighbors who may have security video from outside their home to call the Union County Sheriff's Office.
"It's heart-wrenching. That little boy will never be the same", Smith said.
"It's pretty low, despicable in my book and I can't believe someone would stoop that low to steal money from him", said the boys father. The 9-year-old lemonade vendor said a teenager wearing a similar hat and a black shirt pointed a black handgun at him and took his cash box Saturday afternoon in Monroe, about 30 miles (50 kilometres) southeast of Charlotte.
"You think of a child as young as this being robbed at a lemonade stand - just when you think you've heard it all, something else will surprise you", he told WSOCTV.
David Smith was selling cool drinks in his North Carolina housing development to raise money for his landscaping business.
Deputies located a trail in the woods where a camouflage hat, a black colored BB handgun and the stolen metal tin were recovered.
Mr Smith said that his son will continue to sell lemonade, but with added safety precautions. So far, there aren't any leads on a suspect.