Authorities say a 15-year-old student has been arrested after a homemade explosive went off at his Massachusetts middle school.

Police Sgt. John Delaney said an eighth-grader faces charges of possession of an incendiary device and disrupting school in session after two devices were found Friday at Chestnut Accelerated Middle School in Springfield.

The boy is not being identified because of his age.

Authorities and school officials say two plastic soda bottles filled with a liquid plumbing chemical, tin foil and water were placed in a school stairwell.

A school administrator burned his hand when he touched remnants of one bottle after it exploded. The second device did not go off.

No students were injured, and the school has been evacuated.