CARLISLE, Pa. (AP) — Authorities say a small explosion and fire in a central Pennsylvania eighth-grade science classroom required hospital treatment for seven students and a teacher.

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

A Carlisle Regional Medical Center spokeswoman said five students and a teacher were treated for what she described as minor injuries.

Silverstrim said the cause is under investigation. Crews were able to extinguish the fire quickly, and the school continued with its regular day.

School district officials have not returned messages seeking information about the accident.

Officials at Johns Hopkins said they can't provide information without the patients' names, which have not been disclosed.