A switch malfunction left about 1,500 Central Maine Power customers in Old Orchard Beach temporarily without electricity Sunday night.

According to CMP’s website, 1,496 customers were affected by the outage – roughly 20 percent of its customers in the seaside town.

A CMP dispatcher said the outage was caused by a malfunctioning switch known as an air brake that can be used to shut off power to an area of the grid. The exact nature of the malfunction was still unknown, he said.

CMP said the power was restored to all but three customers shortly after 11 p.m. – about an hour after the outage occurred.