PHILADELPHIA (CBS) – Authorities say over a dozen middle school students at West Oak Lane Charter School knowingly ingested marijuana edibles at school on Friday morning. Philadelphia police and school officials are investigating what they say was a planned event spread through social media.

The school was on lockdown for much of the day as police investigated what happened. They say a seventh-grader bought the marijuana-infused Rice Krispie treats online, brought them to school and gave them to her classmates.

Police and Medic responding to West Oak Lane Charter School. @PhillyPolice say 15 students became sick after ingesting edibles. Police say a 7th grader bought them online, brought them to school and gave them to classmates @CBSPhilly pic.twitter.com/tdomz1wGgH — Howard Monroe (@HMonroeNews) September 27, 2019

At least 15 seventh-graders, around the age of 12, fell ill after eating the treats. None of them needed to go to the hospital.

Parents rushed to the school after hearing about the situation. They say they were notified by voicemail there was an incident at the school, but were never told exactly what happened.

School administrators told Eyewitness News the scheme to buy the edibles and distribute them was plotted through social media.

“Social media drives a lot of these kinds of situations. Parents absolutely need to be focused and monitoring the social media sites that their children are using,” school CEO Dr. Debbera Peoples-Lee said.

The student accused of bringing in the treats may be facing charges.

The incident remains under investigation.

CBS3’s Howard Monroe contributed to this report.