The Union County Sheriff's Office has identified a man who went missing while swimming in the Missouri River near Elk Point Sunday.

Union County Sheriff Dan Limoges says Tom Patterson, 23, of Frostburg, Md. was swimming with his friends southwest of Elk Point on Sunday, when he went missing. Patterson is a student at Briar Cliff University in Sioux City, Iowa.

The search for Patterson resumed at 7 a.m. Monday. Four dogs and three site scan solar units are being used to locate Patterson.

The Union County Sheriff's Office, Dixon County Sheriff's Office, Yankton Search and Rescue, South Dakota and Nebraska Game Fish & Parks, and Brookings Search and Rescue and K-9 Units are participating in the search.