According to USA Today, the accident occurred at the Yellow School at Memorial Drive Presbyterian Church late Tuesday morning.
Six of the children were transported to the hospital with burns. One remained hospitalized Tuesday evening. Five other children were treated for less serious burns by private physicians, and one other child was injured after being trampled.
All of the injured children were 3 and 4 years old.
Employees with the church said the science experiment was being conducted outdoors under supervision. A fire chief later revealed a teacher mixed boric acid with methanol to show flames changing color.
The incident is under investigation.