FARMINGTON — The cause of a power outage affecting 13,600 customers around Franklin County is yet undetermined, said Gail Rice, Central Maine Power spokesman.

A transmission problem at the Sturtevant substation on the Farmington Falls Road is suspected the cause of the outage that occurred shortly before noon, she said.

The company was switching power sources, and most customers had power restored within about 20 minutes.

Towns affected ranged from Weld to Kingfield and Madrid to Chesterville.