Much of central and southern Aroostook County lost electricity Monday afternoon, after what Emera Maine said could be a transmission problem.

The power went out a little after 4 p.m. for all customers from Island Falls north to Caribou, according to Emera spokesman Bob Potts.

While the blackout remains under investigation, Potts said it “appears we had a fault in the transmission line that feeds the region from New Brunswick.”

Emera system operators are working to restore power through a “rolling restoration,” Potts said in an email.

“It takes time to do this but it’s the quickest way to get people back on line while the line workers are patrolling the lines and substations to determine the cause.”

Emera asked that drivers be watchful for utility crews working on the lines.

The company estimated that 9,919 customers were without power as of 8:15 p.m.