FOND DU LAC, Wis. (AP) — A rescue search for two people missing after they were thrown from a canoe in the choppy waters of Lake Winnebago is now a recovery effort, the Fond du Lac County sheriff said Tuesday.

Dispatchers received a 911 call from one of the two individuals about 8:30 p.m. Monday. The canoers were about one mile north of the Fond du Lac River outlet, WLUK-TV reported.

Sheriff’s officials said at the time of the call, both were still in the canoe, but were thrown into the water a short time later. Neither had a life jacket.

Dispatch continued to talk with the caller in the water for several more minutes before the call disconnected.

Conditions on the lake were dangerous at the time, according to authorities. Sustained winds of 25 mph gusted to 40 mph with waves of four to five feet.

Sheriff Ryan Waldschmidt said sonar scanning equipment will be used to try to locate the victims, which were in the early 20s and from the Fond du Lac area. He said the canoe, along with some items from the canoe, have been located.

Multiple agencies are involved in the search. A U.S. Coast Guard helicopter has returned to Traverse City, Michigan because the search has transitioned to a recovery effort, Waldschmidt said.