The search continued Thursday for a northeast Georgia man last seen Monday night on an inner tube with friends at Yellowstone National Park.

Darien Latty, 22, of Demorest, and two other men, all concession workers in the park, were seen floating down the Lamar River near the Yellowstone River, the National Parks Service said. The other two men got out of the water, but Latty was swept downstream in the rushing water, according to witnesses. Floating the river is against park regulations.

Latty was not wearing a life jacket and had lost his inner tube when he was last seen around 7:30 p.m. By Tuesday afternoon, about 50 people were involved in the search for Latty, described as 5 feet 7 inches tall, 140 pounds, with brown hair and brown eyes. The search has involved a helicopter and dogs, the NPS said.

Latty is a 2010 graduate of Habersham Central High School. A family member declined Thursday to speak about the ongoing search.

Anyone with information regarding Latty’s whereabouts is asked to call Yellowstone National Park at 307-344-2642.