A Mahopac family and the surrounding community are mourning the loss of a 17-year-old girl who died of a sudden and unexplained illness.

Hannah Mikus initially suffered a seizure on Monday and was rushed to Putnam Hospital Center, according to her father, Ken Mikus. She was later transferred to Westchester Medical Center, where she died on Tuesday.

Two weeks ago, Ken Mikus says his daughter was treated for a urinary tract infection at a nearby walk-in clinic. The clinic put her on Benadryl Monday, which is when her condition suddenly deteriorated.

Her cause of death has not been determined.

Mikus was preparing to enter her senior year at Mahopac High School, where her father says she was well-liked and a talented lacrosse player.

A service for Mikus will be held Saturday at the Joseph J. Smith Funeral Home in Mahopac.

A GoFundMe page has been set up to raise money for a scholarship in her name.