The Yellowstone County Sheriff's Office recovered the body of a man partially encased in ice from the Yellowstone River at Coulson Park on Wednesday.
"It appears he was frozen in some ice," Sheriff Mike Linder said.
Emergency crews were called to Coulson Park at about 10:45 a.m. after a man who frequents the area found the body floating in the river, Linder said.
Authorities have not yet identified the man and his body was taken to the morgue to be thawed and examined.
The cause of death wasn't known as of 2 p.m., and Linder expected more information to be available later in the week.
"It remains under investigation, and we should know more soon," he said. "A complete and thorough investigation will take place."
Sheriff's officials remained at Coulson Park, in the area across from the ConocoPhillips refinery.
Crews from American Medical Response and the Billings Fire Department initially responded but left the area by noon.