JACKSON, Wyo. -- Searchers on Thursday found three Midwestern sisters who were missing for days in a northwest Wyoming wilderness area.

A helicopter spotted the three about 10 a.m. in Bridger-Teton National Forest, about 25 miles southeast of the resort town of Jackson, said Lori Iverson, spokeswoman for the multiagency task force conducting the search. They were cold and hungry but otherwise healthy, she said.

"The helicopter is flying them to the Swift Creek Trailhead, where the girls' father is, and he'll be driving them out," Iverson said.

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Officials have said the sisters are experienced trekkers who were well-prepared for a backcountry trip. The search began Tuesday after they failed to return from their excursion. They left on June 28 and were scheduled to be in Chicago on Tuesday, Iverson said.

The sisters are Megan Margaret Andrews-Sharer, 25, of Milwaukee; Erin Andrews-Sharer, 22, of Columbus, Ohio; and Kelsi Andrews-Sharer, 16, also of Columbus.

"They were well-prepared for the trip," Iverson said. "They had the appropriate clothing, they had the appropriate gear."

Earlier Thursday, authorities doubled the number of people combing the wilderness to more than 60, and they searched on horseback, on foot and with help from tracking dogs and two helicopters.

The sisters' vehicle was found Wednesday at a wilderness trailhead popular for hiking. But people and wildlife have carved out many alternate trails that can confuse hikers, Iverson said.

"It's very easy, even for experienced people, to get off course and make a wrong turn," she said. "So we simply suspect that the girls made a wrong turn and are looking for an egress out, maybe ending up in a location other than where their vehicle was."

According to CBS affiliate KGWN, relatives said the sisters were believed to have purchased five days worth of food on June 28th.

The Rev. Susan Patterson-Sumwalt of the United Methodist Church of Whitefish Bay, Wisconsin, said the sisters had worshipped there as children and that Megan Andrews-Sharer had worked there until recently.

She resigned recently to work on a farm in Wyoming, Patterson-Sumwalt said.