The employee opened the girl's backpack and found 14 bags of marijuana, and immediately called police.
"My nephew goes here, my daughter goes to school around the corner - that's just crazy," said parent Fatima Mohammed, "where did they get it from? How did they get out of the house with it?"
The incident happened around 1 on Friday afternoon. Police questioned several people, including the girl's parents, eventually figuring out that a family friend is allegedly responsible.
School administrators refused to talk to Eyewitness News, and instead called police to guard the building.
Parents say teachers were tight-lipped as they picked up their kids.
"For them not to inform us, I'm really surprised," said Maxine Smith.
"This place has been around for a long time, it's shocking, said another parent, Shenice Robinson, "no one has ever said anything like that about this place. My child came here because I heard good things about the school."
Kelly Mena, 24, was arrested and charged with Criminal Possession of Marijuana & Criminal Sale of Marijuana
The suspect is a friend of the father, and police say he put the drugs in the backpack the night before and forgot about it.