At least 27 elementary school students have died and at least 100 have been hospitalized after eating improperly prepared cassava roots in a school in San Jose, Philippines.

The snack was caramelized cassava which was apparently purchased from a vendor right outside the school grounds.

When properly prepared, cassava roots are a healthy snack rich in protein and vitamins such as A, B and C. However, if the cassava is not properly prepared, it is a deadly poison. The body will convert part of the food into cyanide which is highly lethal. Even a small amount can prove fatal.

'Some said they took only two bites because it tasted bitter and the effects were felt five, 10 minutes later,' Dr. Harold Gallego of Garcia Memorial Provincial Hospital where many of the victims were taken, told the Associated Press.

The nearest hospital was over 20 miles away so treatment for many of the students was delayed.

A piece of the cassava root in question has been taken to a lab for analysis. Meanwhile, families mourn the loss of children who were poisoned to death at school.