Police are investigating the source of an apparent false alarm at Raymond Elementary School that sent the building into lockdown Tuesday morning for about an hour.

The Cumberland County Sheriff’s Office responded to a “panic lockdown” alarm reported by an outside alarm company at 9:17 a.m.

At the same time, teachers and staff received the same notice on their computers. A staff member at the school also called Cumberland County dispatchers to report the alarm, but also said it may be the result of a “computer glitch.”

Teachers and staff followed procedures and went into lockdown. Sheriff’s deputies responded and combed through the building room by room to ensure there was no threat, said sheriff’s Capt. Scott Stewart.

All parents were notified of the lockdown by the school district.

The accidental lockdown comes after two other schools in Maine responded to possible threats on Monday.

At Baxter Academy in Portland, a threatening message found inside a school bathroom caused police to evacuate the school a short time before it would normally have been dismissed.

The other incident occurred at Lewiston High School. Someone became concerned after overhearing a conversation outside the school and reported it to police, but the heightened security was lifted a short time later when it was determined there was no threat to the school.