Three seventh-grade girls were hospitalized after they ate Rice Krispie treats at school that were possibly laced with an unknown substance, according to the Philadelphia Police Department.
The incident was reported just before 11 a.m. when one of the girls felt lethargic at Martha Washington Elementary School in Philadelphia, police said.
The girls -- one 12-year-old and two 13-year-olds -- were taken to the Children's Hospital of Philadelphia, police said.
One girl was in stable condition. The conditions of the other girls were not immediately known.
One of the students brought the baked good from home, according to the school district.
"The safety of our students is our highest priority," said H. Lee Whack Jr., spokesman for the School District of Philadelphia. "We are cooperating fully with the Philadelphia Police Department on this matter and notifying all school families of what took place."
School district administrators said in a letter to parents: "Any student consuming a dangerous and illegal substance is a serious concern to all of us. Incidents like this put the health and safety of students and staff at risk. Again, we take this very seriously and it will be dealt with according to District policy."