DINOSAUR NATIONAL MONUMENT (AP) — The National Park Service and the Moffat County, Colo., sheriff's office are investigating the apparent drowning of a young boy on the Green River during a rafting trip through Dinosaur National Monument.

Park officials say the boy died Sunday near Upper Disaster Falls in Colorado. The monument straddles the Utah-Colorado line.

Carla Beasley, chief of interpretation at the park, says the name, age and hometown of the boy were not available Monday afternoon.

Helicopters were unable to reach the area Sunday because of steep terrain, stormy weather and nightfall.

Beasley says the group floated out of the area on Monday.