Susan Frank, 63, and Steve Domonkos, 62, left Casper on Thursday morning. They were supposed to return Sunday afternoon, but daughter Stephanie Frank says she has not heard from them and their phones are turned off.
Stephanie's children, 10-year-old Abigayle and 9-year-old Nicholas, went along on the trip. They also have not been heard from since Thursday.
The group of four was said to be headed to Squaretop Mountain, west of the Wind River Reservation between Pinedale and Dubois.
Stephanie says they were driving a late-model blue Chevrolet pickup truck -- possibly a Silverado -- with Casper license plates. They were towing the camper pictured above.