Authorities have initiated extensive search and rescue operations in Yellowstone National Park for two individuals reported missing. A 22-year-old hiker has not been heard from since Tuesday, prompting park rangers and rescue teams to scour the area. In a separate incident, a Yellowstone concession worker has gone missing after a backcountry hike in adverse weather conditions. The National Park Service is asking the public for assistance in locating the missing individuals as search efforts continue in the remote parts of the park.