SANFORD — All systems were “go” for classes at Sanford High School today after a short in a rooftop air handler produced a scent of heat inside the building, an electric circuit board tripped and classes were dismissed a few minutes early on Wednesday.

Superintendent David Theoharides said students were dismissed about nine minutes before the end of classes when a switch on  a rooftop air handler shorted out and created sparks.

“Someone saw it and called the Fire Department,” said Theoharides. Firefighters arrived, and the malfunction was discovered.

It apparently gave off the scent of heat, or what was described as an electrical smell, Theoharides said. The circuit breaker performed as it was designed to do — it tripped, causing some lights to go off and interrupting internet signals.

He said students were sent to their buses.

Theoharides late Wednesday afternoon said the matter had been corrected. He said an alert was sent to parents, explaining what had transpired.