Manila, Philippines ? Wailing parents carried the bodies of their children from hospitals after a snack of cassava — a root that’s poisonous if not prepared correctly — bought from an outside vendor killed 27 and sickened 100 others Wednesday at an elementary school in the south-central Philippines.

With the nearest hospital 20 miles away from San Jose school, in Bohol island’s Mabini town, some victims died while being carried in a variety of vehicles, including three-wheel motorcycle taxis.

Francisca Doliente said her 9-year-old niece, Arve Tamor, was given some of the caramelized cassava by a classmate who bought it from the vendor.

“Her friend is gone. She died,” Doliente told The Associated Press. Her niece was being treated, she said.

The roots of the cassava plant, a major crop in Southeast Asia and other parts of the world, are rich in protein, minerals and the vitamins A, B and C. However, cassava is poisonous unless it is peeled and thoroughly cooked. If it is eaten raw or prepared incorrectly, one of its chemical constituents will be attacked by digestive enzymes and give off the deadly poison cyanide. As little as two cassava roots can contain a fatal dose.