Driving a large motor home can be tricky on the smoothest and straightest of roads, but traveling through Great Smoky Mountains National Park carries its own risks, as seven visitors discovered Monday when their RV slid 100 feet down a slope, injuring six of the occupants.

The accident occurred around noon Eastern standard time when Robert McCanna Reilly III, of Miami, tried to pull the RV off the Newfound Gap Road and onto the shoulder about 3 miles south of Newfound Gap.

However, the motorist was unable to stop the rig before the gravel shoulder narrowed too much for the RV, according to park officials. It fell onto its side and slid about 100 feet down a steep embankment, they added.

Mr. Reilly was uninjured, but the six passengers were. Two of the patients with severe injuries were transported by Mountain Area Medical Airlift to Memorial Mission Hospital in Asheville, North Carolina, the park reported. Four other individuals were transported by Cherokee Tribal Ambulance to Cherokee Hospital with less serious injuries.

Those taken to the Asheville hospital were a 13-year old boy who was in the front passenger seat; and Eduard Koefler, 57, who was in the back of the vehicle, park officials said. The 13-year-old was not wearing a seatbelt and was ejected from the vehicle. Mr. Koefler was removed from inside the vehicle by the occupants.

Park officials identified the other four patients as: Christoper Koefler (18); Ino Reilly, 30; Bridgette Koefler, 56, and Julia Koefler, 10. The Koeflers are all from Austria and were visiting their relatives, the Reillys.

None of the injuries were thought to be life-threatening.

When emergency personnel arrived on the scene all but two of the passengers were alongside the road. The road remained closed as of 4:30 p.m. to allow a crane service to remove the RV from the site.