BAYSIDE, Calif. (AP) — Three third-grade students at a Northern California elementary school were hospitalized after inadvertently eating cannabis gummies, authorities said.

A student shared the gummies with four other kids during their snack recess on Thursday at Jacoby Creek Elementary in the Humboldt County community of Bayside, police and school officials said. The student who brought the edibles to school didn’t know they contained marijuana, they said.

Three children were taken to receive medical attention after they began to display signs of intoxication, Jacoby Creek superintendent and principal Melanie Nannizzi told parents in an email.

All three kids were released from the hospital and are doing well, Nannizzi told the Times-Standard newspaper in Eureka.

The classroom was initially evacuated over concerns the kids might have been reacting to carbon monoxide exposure, Nannizzi told parents.

“This was a frightening incident for our entire school community,” Nannizzi wrote in the email.

The Arcata Police Department is investigating, Officer Heidi Groszmann said.

Groszmann warned parents to keep cannabis products, especially those that look like candy, in a safe spot away from children.