Ten students at Van Nuys Middle School in Los Angeles, California, were evaluated for suspected overdoses during the school day Thursday. 

The children, who were evaluated by Los Angeles Fire Department personnel, were between the ages of 12 and 15 years old. Seven of the 10 students were transported to local hospitals, the LAFD said in a press release, while three were released on scene. 

It has not been confirmed what, if anything, the students may have consumed. In a press conference, the LAFD said it may have “possibly” been “cannabis edibles,” and said that fentanyl, a potent synthetic opioid, was not involved. 

All 10 students were found to be in “mild-to-moderate distress.” Officials have not said what symptoms students experienced. 

The LAFD was first called to the school shortly after 10:30 a.m. PT. By 11:20, five patients on the scene had medical complaints, and by noon, 10 students were being treated for mild symptoms, CBS Los Angeles reported. LAFD said 50 firefighters were at the scene, and crews searched the school premises to ensure that all students were accounted for.