School officials say some students came up with the plot through social media.
"We were in science class and they took this girl and a couple other girls," said Imani Channer, 12. She said the students involved appeared tired and drowsy.
Police and paramedics responded to the school just before 10 a.m.
Action News is told a student reported what happened to school officials. The officials then contacted police.
School officials said the students were taken to the nurse's office and their parents were contacted.
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"They all developed some sort of symptoms, some sort of illness. At this point, it does not appear that they will require hospitalization, but the fire department medics did respond to the school and evaluated them all," Philadelphia Police Captain Sekou Kinebrew said.
However, school officials have a different story of what occurred at the school.
They say none of the students actually exhibited any illness or symptoms. All students were released to their parents.
School officials say there could be disciplinary actions taken against the students who came up with the plan. They say there are cameras in the school that may have captured what exactly happened.
School CEO Debbera Lee pleaded with parents to monitor their children's social media accounts.
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"This is being driven through social media. Parents need to find a way to track what their kids are on, who they're talking to and what kinds of plans they're making," said Lee.
Philadelphia police are leading the investigation.