14 Lowell Elementary students were taken to hospitals Wednesday morning.
Chicago Public Schools says this was just a precaution and all of the affected students are in good condition.
Doctors told one mother it appeared her daughter unwittingly ate candy from a fellow student, which was laced with marijuana.
CPS says the entire matter is under investigation.
Chicago Public Schools released the following statement:
"School officials contacted 911 in response to concerns that a group of students may have ingested an unknown substance earlier this morning. Emergency services providers responded promptly, and a review of the situation is underway."