CARLISLE â?? A small explosion and fire Wednesday in a central Pennsylvania eighth-grade science classroom required hospital treatment for seven students and a teacher.

Carlisle Area School District Superintendent John Friend told reporters that a fireball occurred when some sort of chemicals were mixed together. He said that the teacher put out the fire with an extinguisher, WHTM-TV reported.

Cumberland County public safety spokeswoman Meg Silverstrim said two of the injured children were taken by helicopter from Wilson Middle School in Carlisle to Johns Hopkins Hospital in Baltimore.

Officials at Johns Hopkins said they could not provide information without the patients' names, which were not released.

A Carlisle Regional Medical Center spokeswoman said five students and a teacher were treated for what she described as minor injuries, and all six had been released by midafternoon.

The school continued with its regular day, Silverstrim said.