At least 30 children at an elementary school in California's affluent Orange County have come down with a mysterious rash - and no one knows why.
An outbreak of bites and blisters at Lake Forest Elementary School has left children itching through the night, and worried parents searching for answers.
Ten staff members at the school have also come down with the rashes and five new cases in the Saddleback Valley Unified School District have since been reported.
The outbreak is reportedly appearing as rashes, bites and welts, on anywhere from faces to arms, feet, backs, chests and waistlines, according to parents.
Mosquitoes, fleas, spiders, mites and mice have all been ruled out as the source, said Jared Dever of the Orange County Mosquito and Vector Control.
Dever said bed bugs are also unlikely the cause, as they are noticeable and tend to strike when people are asleep or immobile, he told NBC Los Angeles.