According to WLWT, the tree fell around 2 a.m. at Ryan's Run campground off U.S. 52 southeast of Cincinnati. Patricia Brandenburg, 46, and her 2-year-old granddaughter were killed.
The Brandenburgs were sleeping when the tree came down.
The 2-year-old had a twin sister, who survived. David Brandenburg, 51, also escaped.
The Clermont County Sheriff's Office told WLWT that the camper was "severely damaged."
"The tree went down all the way to the frame," according to Franklin Township Fire Chief Bradley Moore.