An otherwise healthy teenager from Owatonna, Minn., died Tuesday after suffering what relatives described as a flu-like illness, raising concerns about the toll of an influenza season that appears harsher than normal.

Test results were pending late Wednesday afternoon to confirm whether flu played a role in the death of Shannon Zwanziger, 17, described as a shy but fun-loving senior at Owatonna High School.

“Just full of life, full of fun,” said her aunt, Brenda Baska. “She had these beautiful blue eyes. If you looked at her, you could see she had a twinkle.”

Zwanziger was sick with flu-like symptoms and fever for a week. After one trip to the doctor, her parents took her back for a strep test Sunday, when a sore throat made it difficult for her to eat or drink. Her symptoms worsened, and on Tuesday she was airlifted to the Mayo Clinic in Rochester, her uncle said.

Zwanziger had no other health problems, relatives said. Typically, influenza in teens isn’t fatal unless they have underlying conditions such as congestive heart failure that complicate their infections.

“We’re in between being in shock, the numbness of being in shock, and the overwhelming grief,” Baska said.

State health authorities track and confirm flu-related deaths, but aren’t permitted by law to acknowledge personal details of specific cases.

What is certain is that the H3N2 strain of influenza circulating in the U.S. this year is historically associated with harsher flu seasons. Last week’s state flu update showed an uptick in schools reporting cases of flu-like illness in the final week of November, along with the state’s first pediatric death from influenza. Case reports from clinics and long-term-care centers in the state were about average, though, and the total number of hospitalizations so far this season is about average compared with the five prior flu seasons, according to state health data.

Updated influenza activity in Minnesota will be reported Dec. 11.

Owatonna High School was among those filing a flu report with the state, which is required whenever a school is missing 5 percent or more of its students due to fevers and other flu symptoms. But that shouldn’t lead to assumptions, said Principal Mark Randall. “We’ve been very careful about not speculating what the cause of death was.”

The school made counselors available on Wednesday, and the career center was designated as a place for students to talk and grieve. A close friend launched a social media campaign to have Zwanziger elected the high school’s winter snow queen. Family friends started a fundraising drive on the YouCaring website to help with expenses, including travel costs for her sister, who lives on the Misawa U.S. air base in Japan.

Friends said Zwanziger had a fascination with video game design and worked at the GameStop retail store in Owatonna — celebrating Halloween this fall by throwing a party for her co-workers.

Hannah Losey, 18, said her cousin was an “absolute gamer girl” but was as comfortable reading for hours in the library as she was skateboarding or sketching or baking or camping. Zwanziger also had a gift for encouraging friends to take on new challenges, she said; although Losey was terrified of horses, Zwanziger got her to ride last summer.

“I think it might have been a promise of baking cupcakes or something like that,” she said.

Losey, who lives in Tennessee, didn’t know her cousin was sick until Zwanziger was flown to Mayo on Tuesday.

“I had no idea there was anything wrong with her,” she said. “It really appeared out of nowhere.”