The Monona County, Iowa Sheriff Jeff Pratt said on Sunday around 7:22 p.m., the Monona County 911 Center received a call of a person overboard in the Missouri River south of Huff's Access near Blencoe, Iowa.
Sheriff Pratt said a man fell overboard and did not resurface once he was in the water.
A search of the area by both Iowa and Nebraska agencies lasted until 11:30 p.m. and the man wasn't recovered from the water.
Sheriff Pratt said a search will resume Monday and the missing man's name has not been released.
The accident is under investigation by the Monona County Sheriff's Office and Iowa DNR Enforcement. Tekamah Fire Rescue, Washington County Sheriff's Office, Harrison County Sheriff's Office, Iowa State Patrol and Omaha Police Air Wing assisted in the search.