AMHERST COUNTY, Va. (NewsNation) — A group of Virginia elementary school students are recovering after eating gummy bears on Tuesday from a bag that contained residue that tested positive for fentanyl, according to the county sheriff’s office.

“A student brought a sandwich bag containing gummies to school, and then shared those gummies with six classmates during lunch,” said Amherst County Public Schools Superintendent Dr. William Wells.

Not long after, it was clear something was wrong.

“Students who ingested the gummies exhibited symptoms of nausea, vomiting, headache, and some muscle spasm,” said Wells.

The gummies tested negative for foreign substances, but residue in the plastic bag that contained the gummies tested positive for fentanyl in a field test, sheriff’s office spokesperson Lt. Dallas Hill said.

As part of the investigation, the sheriff’s office executed a search warrant at a home in the county and arrested two people who were charged with contributing to the delinquency of a minor, Hill said. One was also charged with possession of a Schedule I or II drug and the other was charged with possession of a firearm by a convicted felon.

The students were all fourth-graders in the same class at the school and all returned home Tuesday evening, Superintendent William Wells said at a news conference on Wednesday. It is believed that the bag was contaminated at home or on the way to school, he said. A sibling of the child who brought the gummies to school in the contaminated bag also had a bag of gummy bears at school, but it did not test positive for fentanyl, Wells said.

NewsNation affiliate WRIC and The Associated Press contributed to this report.