Mabini, Philippines ? Weeping relatives watched as the coffins of some of the 27 schoolchildren who died after eating improperly prepared cassava root were lined up for burial at a Roman Catholic chapel in the central Philippines.

Overcome with grief, Lorenza Asas, mother of 7-year-old Sherwin Asas, stomped her feet on the floor. “I can’t accept that my son is dead,” she said, as her relatives tried to calm her.

The victims, most ages 7 to 13, bought the deep-fried caramelized cassava from vendors during snack time at the San Jose school in Mabini town on the central Philippine island of Bohol.

Another 103 people were hospitalized with severe stomach pains and diarrhea.

While rich in protein, minerals and vitamins, starchy cassava roots are poisonous without proper preparation. The human digestive system can convert part of them into cyanide if they are eaten raw.

At a foothill cemetery, parents, residents and officials watched 12 coffins placed into side-by-side concrete niches.

“Maybe everyone here is still in shock,” Mayor Stephan Rances said with tears in his eyes as workers nailed the coffins shut before sealing the niches with cement. Relatives wept nearby.

Anicita Luyong, 33, grieved over the coffin of her 7-year-old son, Wilfredo Luyong Jr., in her house near the school.

Marivic Sanayan cries as she clings to her son's coffin during a mass burial in Mabini, Philippines. On Thursday sobbing parents buried some of the 27 elementary schoolchildren who died after eating a snack of cassava, a root that's poisonous if not prepared correctly, while 103 other people remained hospitalized with severe stomach pain and diarrhea.

She said the boy, who had wanted to be a soldier, came home crying with severe abdominal pain. He was taken to a hospital but did not survive.

“Our village is poor. Our rice farms are parched. We have no hope of a good harvest this season because there was no rain,” she said. “The youth in the village are striving hard to study because we are poor.”

One of the two vendors also was ill and still hospitalized Thursday, while the other was in police custody to protect her from outraged parents, said the town mayor’s aide, Philip Fuderanan. Authorities have not ruled out criminal charges against the vendors.

Investigators were checking whether the vendors failed to properly cook the cassava and were studying unconfirmed reports that tainted cooking oil was used, said Health Secretary Manuel Dayrit.