Miraculously, three children who were also in the tent were spared.
The giant Sycamore tree, standing 50 to 75 feet tall and estimated to weigh thousands of pounds, fell onto the tent just after 6 a.m.
The father, 46-year-old William Arias, was pronounced dead at the scene, and his wife, 42-year-old Elcetia Arias, was rushed to the hospital in critical condition. Elcetia Arias's condition has since been upgraded to guarded.
The couple's 9-year-old son and 12-year-old daughter, as well as the children's 10-year-old male cousin, escaped injury.
"It was just luck they were in the right part of the tent to escape injury," one official said.
The three children were put in the custody of child services.
The family was from Somerset County and camping in an approved location at Bull's Island Recreation Area in Hunterdon County, near the Delaware River.
New Jersey Department of Environmental Protection spokesman Larry Ragonese compared the likelihood of something like this happening to being struck by lighting.
"There were no weather conditions," he said. "There was very light winds. There was no rain. There were no storms. There was nothing that occured other than the tree decided to uproot from the forest."