VALLEY CITY (AP) - Authorities say divers are searching for a missing woman at Lake Ashtabula, north of Valley City.

Authorities say the 21-year-old woman was swimming off a pontoon and disappeared at about 1:40 a.m. Friday.

Barnes County Sheriff Gene Bjerke says the search was launched early Friday morning.

Authorities say dive teams from Fargo and Valley City, and the National Guard are involved in the search.