Durham police are cautioning parents after snacks made with marijuana were consumed by children at an Oshawa elementary school on two separate occasions.

Police said the first incident happened on May 14 when a Grade 6 student brought home-baked cookies into school as a treat.

“After consuming the cookies, four students (three were 11 years old, one was 12 years old) reported feeling dizzy and euphoric,” police said in a news release.

Durham District School Board called in police to investigate the incident and officers discovered that the cookies were originally made by a parent for a spouse with a medical marijuana license. An older sibling in high school stole some of the batch and several cookies somehow ended up in the sixth grader’s backpack, police said.

The Children’s Aid Society has been called in to conduct a review of that incident.

Police said the cookie incident came just a week after THC-infused gummy bears were eaten by students at the same elementary school, leaving four children in Grade 7 and Grade 8 feeling “dizzy and euphoric.” Police said the gummy bears were brought in by a student, but it is not known how he or she got them.

Police said they are trying to educate parents, students and teachers about the danger of consuming psychoactive chemicals at a young age. Police also circulated images of the pre-packaged gummy bears to staff members so that they would know how to spot them.