ABC News reports that children in California and Illinois have become ill in the last several weeks after eating cookies and brownies made with marijuana.

The cookies were made by a Colorado company that says they are legal because they are sold for medical purposes. The kids apparently didn’t know that; they shared the cookies during lunch and reported feeling nauseated about half an hour later.

In the most recent case, several elementary school students from Vallejo, Calif., got sick after eating marijuana-laced cookies given to one of them by a convenience store clerk.

According to the school district, the children have been released from the hospital and are doing well.

"It’s unclear if any of the children knew the cookies contained cannabis," police Sgt. Jeff Bassett said in a press release. "The packages are not clearly marked.”

Police are still trying to find the person who gave the cookies to the store clerk.