A 25-year-old Oklahoma man was thought to be missing in Yellowstone National Park, officials said Tuesday.

Peter Louis Kastner, of Oklahoma City, became the subject of a search when rangers Monday morning found a car the man had rented parked at the Hellroaring Trailhead in the northern end of the park.

The car, a red 2010 Cadillac STS sedan with Oklahoma plates that Mr. Kastner had rented, had been parked overnight and was not linked to a backcountry permit, park officials said Tuesday afternoon. When rangers contacted the man's family, they reported him missing.

Dog teams were added to the search effort Tuesday afternoon.

The missing man was described as standing 6-foot-1, weighing 185 pounds, and with brown hair and hazel eyes.

The Hellroaring Trailhead is about 3.5 miles west of Tower Junction. The trail runs only about 4 miles, roundtrip, but is considered strenuous. It drops down to the Yellowstone River Suspension Bridge and continues on across a sagebrush plateau following the Hellroaring Creek.

Rangers believe Mr. Kastner might have been in the area for up to two weeks, and might not have been using his own name in any contact with individuals or businesses.

Anyone with information regarding Mr. Kastner was asked to call Yellowstone National Park at 307-344-7381.