The conditions of the students weren't immediately available. A department spokesperson said three were taken to Cape Fear Valley Medical Center for further treatment and evaluation. Three more were treated at the scene.
The school at 1800 Seabrook Rd. was evacuated as a precaution.
Cumberland County schools spokeswoman Renarta Moyd said the experiment ignited in an advanced placement chemistry course when potassium nitrate and table sugar were heated together.
Moyd said the heated mixture ignited as it was being taken outside the laboratory.
One student was taken to Womack Army Medical Center at nearby Fort Bragg and two others to Cape Fear Valley Medical Center.
Firefighters were at the school decontaminating the area. The room also has smoke damage.
The injured students are seniors. Their names were not immediately released.