Rescuers in the U.S. Virgin Islands resumed — and expanded — their search Wednesday for a missing American medical school graduate who hasn't been seen for almost a week, officials said.

Tropical Storm Karen prompted island authorities to briefly curtail efforts Tuesday to find 48-year-old Lucy Schuhmann before resuming their search Wednesday.

The expanded search includes "some of the most remote and rugged areas of" the Virgin Islands National Park, according to a park statement.

"The terrain is very steep and thickly vegetated, while conditions are hot, wet and humid," the statement continued. "Safety of the park staff is of concern as the recent storms have downed trees and other vegetation along hiking trails."

Schuhmann recently graduated from the medical school at the University of Louisville, according to the school and Mary Rowley, the principal medical educator at Ximedus, a prep service for medical exams used by the missing woman.

Schuhmann was a frequent visitor to St. John and had been looking forward to going there after taking her most recent medical exam in Philadelphia on Sept. 12, according to Rowley.

"She's very athletic and she's the type of person who would go off on her own. So that's not unlike her," Rowley told NBC News on Wednesday. "People are starting to lose hope, but I haven't."

Schuhmann is older than almost all of her recent med school grad peers, according to Rowley.

"She decided to go back to school because helping individuals is such a burning desire in her," Rowley said. "She's such a compassionate person."

Schuhmann was reported missing Thursday, after her bags were found at a vacation rental in Coral Bay on St. John, officials said.

Her rental car was found at a parking area in the Virgin Islands National Park, officials said. Rescuers have been concentrating their search on the southern shoreline of the park, near where Schuhmann's car was found.

Divers and snorkelers have investigated the waters off St. John, and a U.S. Coast Guard helicopter has also searched the area, according to a statement Tuesday from the Virgin Islands National Park.