By Michael Rosenfield, WBZ-TV

GREENLAND, NH (CBS) – Fifth grade student Katherine Hartley is back home after a strange and sudden illness at her school Greenland Central.

She says her science class was testing the fats of certain foods like hot dogs, mayonnaise and blue cheese when she and several classmates started feeling sick.

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“Everyone started gagging,” says Katherine.

Her mom got the call to get to the school quickly.

“She looked extremely ashen, I knew that she was ill,” said Katherine’s mother Carole. “What scared her I think the most and alarmed me was that she said her hands were numb.”

In all, 12 fifth-grade students became sick with nausea and other symptoms. Investigators checked out the students and the building.

“All the vital signs were good on the kids,” said Superintendent George Cushing. “We checked the building for gasses, things like that, and that all came back very clean.”

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All of the students were released to their parents and classes resumed for everyone else.

“I think with the flu that’s going around, I think that’s what we have,” said Greenland Fire Chief Ralph Cresta. But authorities cannot explain why everyone would get so sick and at the same time.

Carole Hartley thinks it’s more likely the sudden illness had something to do with the science project.

“I’m just guessing that because the kids were touching probably bacteria that had festered in the food…maybe the kids touched their noses, or they were all breathing in air that was not clean,” said Hartley.

Greenland Police Chief Tara Laurent says there is nothing criminal or suspicious to investigate.

The case is being reported to the state’s Public Health Nurse, according to a letter to parents from the school’s principal Peter Smith.

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“It was kind of gross, probably not for the boys,” said Katherine.