A tree fell on a tent at a New Jersey campsite this morning, killing a 46-year-old man and critically injuring his wife, officials say. The couple's two children and a nephew escaped harm.

The Sycamore tree weighing thousands of pounds toppled in fair weather about 6 a.m. at on Bull's Island State Park in the Delaware River in Hunterdon County, said Abbie Tang-Smith, a spokeswoman for the state Department of Environmental Protection.

The man was pronounced dead at the scene and his 42-year-old wife was airlifted to a Trenton area hospital, where she was reported to be in guarded condition, said Tang-Smith.

She said the couple's 12-year-old daughter, 10-year-old son and 9-year-old nephew were not hurt, and were to be placed in the custody of relatives.

The family is from Somerset County, N.J., Tang-Smith said.

Officials are trying to determine why the tree fell.